Q1:Circuit diagram is a simplified conventional pictorial representation of an_______________
Ans: Electrical circuit
Q2:A circuit diagram uses standard symbols for electric components. True/ False.
Ans: True.
Q3:Define electric circuit.
Ans: A closed path formed by connecting electrical components allows electric current to flow. This arrangement is known as an electric circuit.
Q4:What is a cell holder?
Ans: A compartment that holds two or more cells together to form a battery is called a cell holder.
Q5:The combination of two or more cells is called a __________________.
Ans: Battery
Q6:A circuit is said to be open circuit or complete when current flows through it. True/ False.
Ans: False
Q7:What is a battery?
Ans: A combination of two or more cells connected together is called a battery. It is formed by connecting the positive terminal of one cell to the negative terminal of another.
Q8:The symbol for a battery is
a.
b.
c.
d. None of These
Ans: C
Q10: Draw the symbol for an electric bulb in an electric circuit.
Ans: Symbol of Electric bulb
Q9:What is a circuit diagram?
Ans: A circuit diagram is a simplified representation of an electrical circuit using symbols to depict various components.
Q10:Why do we use copper wires in electrical circuits?
Ans: Copper is a good conductor of electricity, which allows the current to flow easily through the wires.
Q11:A Longer line in the symbol for a cell represents its ——- terminal.
Ans: Positive
Q12:What is an electric circuit?
Ans: Electric Circuit: The closed path in which electric current flows.
Q13:What happens when the current is switched ‘on’ in a room heater?
Ans: It becomes red hot and gives out heat.
Q14:Would any of the bulbs glow when the switch is in the ‘OFF’ position in a circuit?
Ans: No, the bulb will not glow when the switch is “OFF” because there is no closed circuit for current to flow.
Q15: What type of electricity is used in homes and industries? Ans: Alternating Current (AC).
Q16: What happens if the filament in an incandescent lamp breaks? Ans: The lamp stops glowing because the circuit is broken.
Q17: How does a torchlight produce light? Ans: By passing current through a lamp powered by electric cells.
Q18: What is the purpose of using insulators in circuits? Ans: To prevent electric shocks and ensure safety.
Q19: What material is used to make the body of most electric cells? Ans: Metal.
Q20: What direction does current flow in a circuit? Ans: From the positive terminal of the cell to the negative terminal.
Q1:The substances used to test whether a substance is acidic or basic are known as ________
Ans: The substances used to test whether a substance is acidic or basic are known as Indicators
Q2:Name the most commonly used indicator.
Ans: Litmus paper
Q3:From where do we extract litmus to be used as an indicator?
Ans: Lichens
Q4:In acidic solution, litmus paper turns into ______
Ans: In acidic solution, litmus paper turns into Red Litmus paper is a pH indicator that turns red in acidic solutions, indicating the presence of acids.
Q5:In basic solution, litmus paper turns into ____
Ans: In basic solution, litmus paper turns into Blue Litmus paper changes to blue in basic solutions, indicating the presence of bases.
Q6:In distilled water, litmus paper turns into _________
Ans: In distilled water, litmus paper turns into purple Litmus paper remains purple in neutral distilled water, as it is neither acidic nor basic.
Q7:The reaction between an acid and a base is known as _________
Ans: The reaction between an acid and a base is known as neutralization. Neutralization is the chemical reaction that occurs when an acid and a base react to form water and a salt.
Q8: Red rose indicator turns acidic solutions _______
a. Dark pink b. Purple c. Blue d. None of these
Ans: a. Dark pink China rose indicator changes to dark pink in acidic solutions, indicating their acidic nature.
Q9:Red/ China rose indicator turns basic solutions to ______
a. Dark pink b. Purple c. Blue d. Green
Ans: d. Green The China rose indicator changes the colour of basic solutions to green. In contrast, it turns acidic solutions to dark pink.
Q10:Salt and water are produced in the neutralization process with the evolution of ____________
Ans: Salt and water are produced in the neutralization process with the evolution of Heat
Q11:Name the acid present in our stomach.
Ans: HCL is present in our stomach. Hydrochloric acid helps break down food and activates digestive enzymes, facilitating the digestion process.
Q12:Name the acid present in the sting of an ant.
Ans: Formic acid is present in the sting of an ant.
Q13:State the nature of the soap solution.
Ans: Basic
Q14:State the nature of baking soda.
Ans: Basic
Q15:State the nature of lemon juice.
Ans: Acidic
Q16:Why does lemon juice and orange juice taste sour?
Ans: Because they contain acids.
Q17:Why does baking soda taste bitter?
Ans: Because it is basic in nature.
Q18:State one property of acids.
Ans: Acids are sour in taste.
Q19:State one property of bases.
Ans: Bases are bitter in taste.
Q20:Tina rubs a solution between her fingers and feels soapy; what is the nature of that solution?
Ans: Basic
Q21:Complete the following reaction: HCl + NaOH —-> ______ + H2O
Ans: NaCl
Q22:Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. Its nature _______________
Ans: Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. Its nature is Basic
Q23:The wastes of many factories contain____________
Ans: The wastes of many factories contain Acids
Q24:Blue litmus paper is dipped in a solution. It remains blue, what is the nature of the solution?
Ans: Basic
Q25:Hydrogen ion is common to all acids. True/False
Ans: True
Q26:Name a base that is also used in soda acid fire extinguishers.
Ans: Baking soda.
Q27:Aqueous solution of acid conducts electricity due to ______________ present in it.
Ans: ion
Q28:Define pH.
Ans: pH is the measure of the Acidity or Alkalinity of a solution. The term pH stands for a negative log of hydrogen ion concentration.
Q29:The bases that dissolve in water are known as alkalies. True/ False.
Ans: True
Q30:Phenolphthalein becomes colourless in __________ and pink in_________.
Ans: Colourless in acid and pink in base.
PhenolphthaleinQ31:Name the acid present in vinegar.
Ans: Acetic acid
Q32:Name the acid present in lemon.
Ans: citric acid
Q33:Change of colour in an acid or base depends on
a. Type of indicator b. The acidic property of that substance c. Basic property of that substance d. None of these
Q1: What is the shape of the Earth’s orbit around the Sun? Answer: The Earth moves around the Sun in a nearly circular path called an orbit.
Q2: What inspired real scientific explorations of flight? Answer: Paper planes helped scientists understand how objects can fly through the air.
Q3: What is the duration of the Earth’s revolution around the Sun? Answer: It takes the Earth one whole year (365 days) to complete one trip around the Sun.
Earth’s RevolutionQ4: What does the tilt of the Earth’s axis cause? Answer: The tilt makes different parts of Earth get sunlight differently, creating seasons.
Q5: What can be explored with electric batteries, lamps, and wires? Answer: These tools help us study how electricity works and flows.
Q6: What happens to materials when they are heated? Answer: Heating can make materials change their shape, size, or state.
Q7: What is one example of an irreversible change? Answer: Once a battery is used up, it cannot be changed back to new again.
Reversible and Irreversible ChangesQ8: How does water flow in the environment? Answer: Water moves below the ground through soil and rocks.
Q9: What are life processes essential for survival? Answer: Eating gives energy needed for all life activities.
Q10: Do plants also need food to grow? Answer: Plants make their own food using sunlight to grow healthy.
Q11: What was the way early humans measured time? Answer: They used the length and position of shadows to tell the time.
Q12: Why is light important for us? Answer: Light helps our eyes see things around us.
Q13: What causes eclipses? Answer: Eclipses happen when one object’s shadow falls on another.
EclipsesQ14: How does the Earth rotate to cause day and night? Answer: Earth spins around its axis, making day and night.
Q15: How does the Earth’s movement around the Sun affect us? Answer: As Earth moves around the Sun, the tilt causes different seasons.
Q16: What happens during a solar eclipse? Answer: The Moon blocks the Sun’s light, causing a solar eclipse.
Q17: What is a lunar eclipse? Answer: The Earth’s shadow falls on the Moon, causing a lunar eclipse.
Q18: Can we safely view a lunar eclipse with our naked eye? Answer: Lunar eclipses are safe to watch without special glasses.
Q19: What causes the stars to appear to move in the sky? Answer: Earth’s spinning makes stars seem like they move across the sky.
Q20: How is the Earth’s axis related to the seasons? Answer: The slant (tilt) of Earth’s axis causes seasons to change.
Q1: The Earth rotates on its axis in approximately how many hours?
a) 12 hours
b) 24 hours
c) 48 hours
d) 365 days
Answer: b) 24 hours
Q2: What causes the day and night cycle on Earth?
a) The Earth’s revolution around the Sun
b) The Earth’s rotation on its axis
c) The Sun’s movement across the sky
d) The Moon’s orbit around the Earth
Answer: b) The Earth’s rotation on its axis
Q3: Which direction does the Earth rotate in?
a) From East to West
b) From West to East
c) From North to South
d) From South to North
Answer: b) From West to East
Q4: A total solar eclipse occurs when:
a) The Earth moves between the Moon and the Sun
b) The Moon moves between the Earth and the Sun
c) The Sun moves between the Earth and the Moon
d) The Earth moves away from the Sun
Answer: b) The Moon moves between the Earth and the Sun
Q5: Why do we experience different seasons on Earth?
a) Due to the Earth’s rotation
b) Due to the tilt of the Earth’s axis
c) Due to the Moon’s position
d) Due to the Earth’s distance from the Sun
Answer: b) Due to the tilt of the Earth’s axisFill in the Blanks
Q1: The Earth completes one revolution around the Sun in __________ days.
Answer: 365 days
Q2: The Earth’s axis is tilted at an angle of __________ degrees with respect to its orbit.
Answer: 23.5 degrees
Q3: The Moon can block sunlight from reaching the Earth, causing a __________ eclipse.
Answer: solar
Q4: The Sun rises in the __________ and sets in the __________.
Answer: East, West
Q5: During a lunar eclipse, the Earth comes between the __________ and the Moon.
Answer: SunTrue/False Questions
Q1: The Earth’s rotation causes the cycle of day and night.
Answer: True
Q2: During a solar eclipse, the Earth moves between the Sun and the Moon.
Answer: False
Q3: The Moon is larger than the Sun, so it can block the Sun’s light completely during a solar eclipse.
Answer: False
Q4: The Sun’s light gets blocked during a lunar eclipse.
Answer: False
Q5: The tilt of the Earth’s axis is responsible for the changing seasons.
Answer: TrueVery Short Answer Questions
Q1: What is the cause of the apparent motion of the Sun in the sky?
Answer: The apparent motion of the Sun is caused by the Earth’s rotation around its axis.
Q2: Why do we experience different seasons on Earth?
Answer: Different seasons occur due to the tilt of the Earth’s axis while it revolves around the Sun.
Q3: What is a solar eclipse?
Answer: A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking the Sun’s light.
Q4: What is a lunar eclipse?
Answer: A lunar eclipse occurs when the Earth passes between the Sun and the Moon, casting a shadow on the Moon.
Q5: In which direction does the Earth rotate?
Answer: The Earth rotates from West to East.Long Answer Questions
Q1: Explain the phenomenon of day and night on Earth.
Answer: Day and night occur because the Earth rotates on its axis. As the Earth rotates, one half of the planet faces the Sun, experiencing daylight, while the other half is in darkness, experiencing nighttime. This rotation takes approximately 24 hours, causing a complete cycle of day and night.
Q2: Describe the process of a solar eclipse and how it occurs.
Answer: A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking the Sun’s light. The Moon’s shadow falls on the Earth, causing a temporary period of darkness. Depending on the alignment, it can be a total solar eclipse, where the Sun is completely blocked, or a partial solar eclipse, where only a part of the Sun is obscured.
Q3: What is the effect of the Earth’s tilt on the seasons?
Answer: The tilt of the Earth’s axis, combined with its revolution around the Sun, causes different parts of the Earth to receive varying amounts of sunlight at different times of the year. This variation in sunlight results in the four seasons: spring, summer, autumn, and winter, each with different lengths of days and nights.
Q4: How does the Earth’s rotation lead to the apparent motion of stars in the sky?
Answer: As the Earth rotates on its axis, the stars appear to move across the sky. In the Northern Hemisphere, stars appear to move in a circular path around the North Star. This motion is due to the Earth’s rotation, which gives the illusion that the stars are moving from east to west.
Q5: What are the differences between a solar eclipse and a lunar eclipse?
Answer: A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking the Sun’s light. A lunar eclipse occurs when the Earth passes between the Sun and the Moon, casting a shadow on the Moon. Solar eclipses are visible only in small areas, while lunar eclipses can be seen from a much larger part of the Earth.
Answer: False Explanation: It reflects sunlight and does not emit its own light.
(b) Transparent materials allow no light to pass through.
Answer: False Explanation: Transparent materials allow almost all light to pass.
(c) A kaleidoscope forms changing symmetrical patterns using mirrors.
Answer: True Explanation: It uses reflections of colored objects.
(d) Light can travel through a bent pipe easily.
Answer: False Explanation: Light travels in a straight line, not through curves.
(e) A plane mirror forms a virtual image.
Answer: True Explanation: The image cannot be projected on a screen.
Fill in the blanks.
(a) Objects that emit their own light are called ___________.
Answer: Luminous objects Explanation: These include the Sun, fireflies, and electric bulbs.
(b) Light travels in a __________ line under normal conditions.
Answer: Straight Explanation: This is known as rectilinear propagation.
(c) An image formed by a plane mirror is laterally __________.
Answer: Inverted Explanation: Left appears as right in the mirror image.
(d) Opaque objects form the __________ shadows.
Answer: Darkest Explanation: They completely block light from passing through.
(e) A __________ camera forms an inverted image on a screen.
Answer: Pinhole Explanation: It uses a tiny hole to project an upside-down image.
Answer the Following Questions
Q.1. What is a luminous object?
An object that produces its own light.
Q.2. Give one example of a translucent material.
Tracing paper.
Q.3. What is the direction of light travel called?
Rectilinear propagation.
Q.4. Which device uses two mirrors to see over obstacles?
Periscope.
Q.5. What do we call the left-right reversal in a mirror image?
Lateral inversion.
Q.6. What happens when light falls on a polished or a shiny surface?
When light strikes a polished or shiny surface, it is primarily reflected. This reflection occurs due to the smoothness of the surface, which allows light to bounce back in a consistent direction.
The light does not scatter but reflects at the same angle it hits the surface.
Common examples of such surfaces include mirrors, stainless steel, and calm water.
This property is what makes these surfaces appear shiny and allows us to see reflections.
Q.7. What is reflection of light?
The reflection of light occurs when a light ray bounces back after hitting a surface. Key points include:
Light travels in straight lines.
When light strikes a smooth surface, it changes direction.
This change in direction is known as reflection.
Common reflective surfaces include mirrors and calm water.
Q.8. Why we are not able to see the candle flame through a bent pipe?
We cannot see the candle flame through a bent pipe due to the way light travels. Here are the key points:
Light travels in straight lines.
A bent pipe alters the path of light, preventing it from reaching our eyes.
Thus, the flame is not visible when viewed through the bent pipe.
Q.9. How can we change the path of light?
We can change the path of light by using any shiny or polished surface. Here are some examples:
A stainless steel plate can redirect light.
A steel spoon acts like a mirror.
The surface of water can also reflect light.
In essence, any shiny surface can alter the direction of light.
Q.10. What happens when light falls on a mirror?
A mirror changes the direction of light that hits it. This process is known as the reflection of light.
When light strikes a mirror, it bounces back.
This change in direction allows us to see our reflection.
Mirrors can be made from various shiny surfaces, including polished metals and glass.
(i) The food synthesized by the plants is stored as starch. Ans: True View Answer
(ii) Plants take carbon dioxide from the atmosphere mainly through their leaves. Ans: True View Answer
Stomata
(iii) Only green leaves can perform photosynthesis. Ans: False View Answer
(iv) Starch turns blue-black when tested with iodine. Ans: True View Answer
(v) Phloem carries water and minerals from the soil. Ans: False View Answer
Fill in the Blanks
(i) In photosynthesis solar energy is captured by the pigment called ____. Ans: Chlorophyll. View Answer
Chlorophyll & Chloroplast
(ii) During photosynthesis plants take in ____ and release ____ . Ans: Carbon dioxide, oxygen View Answer
(iii) ____ in plant take in carbon dioxide from the air for photosynthesis. Ans: Stomata View Answer
(iv) ____ are the products of photosynthesis. Ans: Glucose and oxygen View Answer
Photosynthesis
(v) Food made by leaves is transported by the __________. Answer: Phloem View Answer
(vi) During respiration, plants use __________ to break down glucose. Answer: Oxygen View Answer
Answer the Following Questions
Q.1. From where do plants get raw materials to prepare their food?
Plants get raw materials to prepare their food from their surroundings.
Carbon Dioxide: Absorbed from the air through stomata in the leaves.
Water: Taken up from the soil through the roots.
Sunlight: Captured by chlorophyll in the leaves. The energy from sunlight is crucial for converting carbon dioxide and water into glucose.
Q.2. What is the ultimate source of energy for all living organisms?
Sun is the ultimate source of energy for all living organisms.
It provides the necessary light energy that plants use to perform photosynthesis, which is the foundation of most food chains.
Plants convert this solar energy into chemical energy in the form of glucose, which is then consumed by herbivores and further by carnivores, making the sun essential for life on Earth.
Q.3. What are the other parts of plant where photosynthesis occurs except leaves?
While leaves are the primary site for photosynthesis, other green parts of the plant can also perform this process. These include:
Green Stems: Some plants, like cacti and young stems of other plants, can carry out photosynthesis due to the presence of chlorophyll.
Green Branches: Similar to stems, branches that have green tissues can also contribute to photosynthesis.
Q.4. What are stomata?
Stomata are tiny pores found primarily on the underside of leaves. They play a vital role in:
Gas Exchange: Allowing carbon dioxide to enter the leaf for photosynthesis and oxygen to exit as a by-product.
Transpiration: Enabling water vapor to leave the plant, helping to regulate temperature and maintain nutrient flow.
Q.5. What is chlorophyll?
Chlorophyll is a green pigment found in the leaves of all green plants. It plays an essential role in photosynthesis by capturing the energy from sunlight.
This pigment absorbs light, especially sunlight, which is then used to convert carbon dioxide and water into glucose (a sugar) during photosynthesis.
The presence of chlorophyll is also what gives plants their characteristic green color.
Q.6. What is plant respiration and how is it different from photosynthesis?
Respiration is the process where plants break down glucose using oxygen to release energy. It happens in all parts of the plant. The word equation is: Glucose + Oxygen → Carbon dioxide + Water + Energy. Unlike photosynthesis, which occurs only in green parts and in light, respiration happens all the time and in all parts of the plant.
Q.7. Why do we boil the leaf in alcohol when we are testing it for starch?
In a starch test, we boil the leaf in alcohol to remove its chlorophyll, the green pigment that masks the presence of starch.
When testing for starch in leaves, we need to see a color change to confirm the presence of starch.
After removing chlorophyll by boiling the leaf in alcohol, the leaf becomes pale.
Once iodine solution is added, it reacts with the starch in the leaf, turning it blue-black.
This confirms that starch is present, proving that photosynthesis has taken place.
Q.8. What is the role of leaves in food preparation? How is starch tested in a leaf?
Leaves act as the food factories of plants because they contain chlorophyll and capture sunlight. They use sunlight, water, and carbon dioxide to make food. The food is stored as starch. To test for starch, the leaf is boiled and treated with iodine solution. If starch is present, it turns blue-black in color.
Q.9. Describe how water and minerals are transported in plants.
Water and minerals are absorbed by the roots from the soil. These are transported upward to the stems, leaves, and flowers through xylem tissue. The xylem acts like a pipeline. This supply is necessary for photosynthesis and plant growth. Without water, plants can wilt or die.
Q.10. How do plants transport food to different parts of the body?
Food made in the leaves through photosynthesis is sent to all parts of the plant. The phloem tissue carries glucose and starch from the leaves to roots, stems, and fruits. This ensures that even non-green parts of the plant get the energy they need to grow and store food.
(iv) The ruminants bring back swallowed grass into their mouth and chew it for some time.
True
(v) We chew the food with the teeth and break it down mechanically into small pieces.
True
(vi) Large intestine receives digested and absorbed food.
False
Q.2. Fill in the blanks.
(i) The main steps of nutrition in humans are ____, ____, ____, ____ and ____.
ingestion, digestion, absorption, assimilation and egestion.
(ii) The largest gland in the human body is ____.
liver
(iii) The stomach releases hydrochloric acid and ____ juices which act on food.
digestive
(iv) The inner wall of the small intestine has many finger-like outgrowths called ____.
villi
(v) Amoeba digests its food in the food ____.
vacuole
(vi) We chew the food with the ____ and break it down mechanically into small pieces.
teeth
Answer the following Questions
Q.3. Where are fats digested in the body?
Fats are primarily digested in the small intestine.
Q.4. What kills bacteria that enter along with the juices to act?
The acid kills many bacteria that enter along with the juices to act. This process helps to maintain a safe environment for digestion and prevents the growth of harmful bacteria.
Q.5. Where are faeces formed in the human body?
Faeces are formed in the human body in large intestine.
Q.6. Where food is absorbed in our body?
Absorption of food takes place in small intestine.
Q.7. Where faeces are stored?
Faeces are stored in rectum.
Q.8. What does saliva do to food in our mouth?
The saliva breaks down the starch into sugars.
Q.9. What is rumen?
Rumen is a large, sac-like structure found in ruminants, such as cattle and deer.
Q.10. What does animal nutrition include?
Animal nutrition includes nutrient requirement, mode of intake of food and its utilisation in the body.
Q.11. What are the different modes of feeding in animals?
Different modes of feeding in animals include:
Scraping – removing food from surfaces.
Chewing – breaking down food into smaller pieces.
Sucking – drawing in liquids, like nectar.
Capturing and swallowing – catching prey whole.
Filtering – sifting tiny food particles from water.
Q.12. What are ruminant animals?
The grazing animals like cows, buffaloes and deer are known as ruminants.
Q.13. What do pancreatic juices digest?
The pancreatic juice plays a crucial role in digestion by acting on:
Carbohydrates – breaking them down into simpler sugars.
Fats – converting them into fatty acids and glycerol.
Proteins – transforming them into amino acids.
Overall, pancreatic juice helps in simplifying these food components for better absorption in the body.
Q.14. What do you mean by rumination?
Rumination is a process that occurs in certain animals, known as ruminants. It involves the following steps:
Animals quickly swallow their food, which is often grass.
The food is stored in a part of the stomach called the rumen.
Later, the partially digested food, known as cud, returns to the mouth.
The animal then chews the cud thoroughly before swallowing it again.
This process helps in the digestion of tough plant materials, particularly cellulose, which many animals, including humans, cannot digest effectively
Q.15. What are the main steps involved in the process of respiration in animals?
The main steps of respiration in animals include inhalation, where oxygen is taken into the body; gas exchange in the lungs or tissues, where oxygen is exchanged for carbon dioxide; and exhalation, where carbon dioxide is expelled from the body. This process is crucial for supplying oxygen to cells and removing waste gases.
False Explanation: The SI unit of speed is metre per second (m/s).
(ii) Candle clocks were used to measure time in ancient India.
False Explanation: Candle clocks were used in other cultures; India used Ghatika-yantras.
(iii) In non-uniform motion, the speed of the object remains the same.
False Explanation: In non-uniform motion, the speed changes.
(iv) All pendulums of the same length have the same time period at the same location.
True Explanation: Time period depends only on the length, not the mass.
(v) Distance is measured in metres and time in seconds.
True Explanation: These are standard SI units.
Q.2. Fill in the blanks. (i) The metallic ball is called the ____ of the pendulum.
bob The term ‘bob’ refers to the weight or mass at the end of a pendulum, which swings back and forth during oscillation.
(ii) The symbols of all units are written in ____.
singular Unit symbols are conventionally written in singular form to maintain consistency and clarity in scientific communication.
(iii) The time taken by the pendulum to complete one oscillation is called its ____.
time period The ‘time period’ is defined as the duration it takes for a pendulum to return to its original position after completing one full swing.
(iv) One microsecond is one ____ of a second.
millionth A microsecond is a unit of time equal to one millionth (10-6) of a second, commonly used in scientific contexts.
(v) A nanosecond is one ____ of a second.
billionth A nanosecond is a unit of time equal to one billionth (10-9) of a second, often used in computing and telecommunications.
(vi) The distance-time graph for the motion of an object moving with a constant speed is a ____.
straight line A straight line on a distance-time graph indicates uniform motion, where the distance covered is directly proportional to time.
Answer the following Questions
Q.3. Give an example of oscillatory motion.
The to and fro motion of a simple pendulum is a clear example of oscillatory motion. Here’s a brief overview:
A simple pendulum consists of a small weight, known as the bob, attached to a string or thread.
When the bob is pulled to one side and released, it swings back and forth around its mean position.
This back-and-forth movement is repeated in a regular pattern, making it a periodic motion.
Q.4. What is uniform motion?
An object that moves in a straight line at a constant speed is described as being in uniform motion. This means:
The speed does not change over time.
The distance covered is proportional to the time taken.
The motion can be represented by a straight line on a distance-time graph.
Q.5. An object moving along a straight line with a constant speed is said to be in uniform motion.
Vehicle A is moving faster. The speed of a vehicle is determined by the distance it covers in a specific time frame. Key points include:
A vehicle that travels a greater distance in the same time interval has a higher speed.
For example, if Vehicle A covers 100 metres in 5 seconds and Vehicle B covers 80 metres in the same time, Vehicle A is faster.
Speed can vary; the same vehicle may move faster or slower at different times.
Q.6. What is distance-time graph?
A distance-time graph visually represents how far an object travels over time. Key points include:
It shows the speed of an object.
A straight line indicates constant speed.
If the line is curved, the object’s speed is changing.
Q.7. What is oscillatory motion?
The to and fro motion of an object is known as oscillatory motion.
Q.8. What is non-uniform motion?
Non-uniform motion occurs when an object’s speed changes while moving along a straight line. Key points include:
The speed is not constant.
Motion can vary from slow to fast.
It contrasts with uniform motion, where speed remains constant.
Q.9. What is the basic unit of speed?
The basic unit of speed is the metre per second (m/s).
Q.10. A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?
Number of oscillations = 20 Total time taken to complete 20 oscillations = 32 s Time period = Total time taken/Number of oscillations = 32/20 = 1.6s
Q.11. When pendulum is said to have one complete oscillation?
The pendulum is said to have completed one oscillation when its bob, starting from its mean position B, moves to A, to C and back to B.
Q.12. Explain how in ancient time a day, a month and a year were measured?
Our ancestors observed that many natural events occur at regular intervals:
The day was defined as the time between one sunrise and the next.
A month was measured from one new moon to the next.
A year was determined by the time it takes for the Earth to complete one revolution around the sun.
Q.13. The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.
Distance between two stations = 240 km Time taken to cover this distance = 4 hours Speed = Distance/Time Taken = 240/4 = 60km/h
Q.14. Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s, calculate the distance between her house and the school.
Time taken = 15 min = 15 x 60 = 900 seconds Speed = 2 m/s Distance = Speed x Time = 2 x 900 = 1800 m = 1800/1000 = 1.8 km
Q.15. What is speedometer?
A speedometer is a device that measures and displays the speed of a vehicle.
It is commonly found on the dashboards of cars, motorcycles, and scooters.
The speed is usually shown in kilometres per hour (km/h).
Speedometers help drivers maintain safe speeds while driving.
Q.16. What are quartz clocks?
Quartz clocks are timekeeping devices that use an electric circuit powered by one or more cells.
They are known for their high accuracy in measuring time.
Quartz clocks have largely replaced older clock technologies.
The precision of quartz clocks is significantly better than traditional clocks.
(i) Metals are poor conductors of heat. Ans: False
Metals are good conductors of heat.
(i) Land breeze occurs during the night.
Ans: True
At night, cooler land air moves towards the warmer sea.
(i) Dark-colored clothes absorb less heat than light-colored clothes.
Ans: False
Dark-colored clothes absorb more heat.
(i) Water vapor released by plants is called transpiration. Ans: True
It is a natural process where plants release water into the air.
(i) Radiation requires air or water to transfer heat. Ans: False
Radiation can occur in empty space, such as sunlight.
Q.2. Fill in the blanks.
(i) The hotness of an object is determined by its ____.
temperature
(ii) Temperature is measured in degree ____.
celsius
(iii) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ____.
conduction
(vi) Dark colored clothes are preferred during ____.
winter
(v) Poor conductors are known as ____.
insulators
Answer the following Questions
Q.3. Does the transfer of heat by radiation require any medium?
The transfer of heat by radiation does not require any medium.
Q.4. What is the concern associated with the use of mercury thermometers?
There is a lot of concern over the use of mercury in thermometers. Mercury is a toxic substance and is very difficult to dispose of if a thermometer breaks.
Q.5. How water get heated when kept on flame?
When water is heated, the water near the flame gets hot. Hot water rises up. The cold water from the sides moves down towards the source of heat. This water also gets hot and rises and water from the sides moves down. This process continues till the whole water gets heated. This mode of heat transfer is known as convection.
Q.6. Which device is used to measure temperature?
Thermometer is used to measure temperature.
Q.7. How does heat flow from one object to another?
Heat flows from a hotter object to a colder object.
Q.8. Do all hot bodies radiate heat?
Yes, all hot bodies radiate heat.
Q.9. How does heat transfer in solids?
In solids, generally, the heat is transferred by the process of conduction.
Q.10. What is Conduction?
The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction.
Q.11. Explain the process of conduction with an example.
Conduction is the transfer of heat in solids through direct contact. In this process, heated particles vibrate and pass energy to nearby particles. For example, when a metal pan is placed on a flame, heat travels from the bottom to the entire surface, making the pan hot. Metals are used for cooking because they are good conductors of heat.
Q.12. What is convection and how does it affect coastal areas?
Convection is heat transfer in liquids and gases where warm particles rise and cool ones sink. In coastal areas, during the day, land heats up faster than sea, causing a sea breeze. At night, land cools faster, creating a land breeze. These breezes are examples of convection currents and provide comfort in coastal climates.
Q.13. Describe radiation and give two real-life applications.
Radiation is the transfer of heat through invisible waves, without needing a medium. For example, the Sun heats the Earth through radiation. Another example is the warmth felt near a fire. Light-colored clothes reflect radiation, keeping us cool, while dark-colored clothes absorb heat, keeping us warm in winter.
Q.14. How does the water cycle help in redistributing water on Earth?
The Sun’s heat drives the water cycle through evaporation, condensation, precipitation, and seepage. Water evaporates from oceans and lakes, forms clouds, and falls back as rain or snow. Some of this water seeps underground to become groundwater. This cycle keeps water circulating and available across regions.
Q.15. What are ice stupas and how do they help conserve water in Ladakh?
Ice stupas are cone-shaped ice structures built in Ladakh to store water in winter. Stream water is frozen in these shapes and melts slowly in spring, providing water for farming. They help solve water scarcity in dry, mountainous areas and are an example of traditional knowledge used for modern conservation.
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