Perfect for revision and assessing comprehension of Chapter 8 topics in science.
1) What does the distance moved by an object in unit time indicate?
Answer: The distance an object moves in unit time indicates its speed.
2) What makes an object slow down, go faster, or change its direction of motion?
Answer: A force can make an object slow down, go faster, or change its direction of motion.
3) What is a force?
Answer: A force is a push or a pull that can change the motion of an object.
4) What can a force do to the bodies it applies to?
Answer: A force can change a body's speed, direction, or shape.
5) What actions are often used to describe certain tasks that result in a change in the state of motion of an object?
Answer: Actions like picking, opening, shutting, kicking, hitting, lifting, flicking, pushing, and pulling are often used to describe tasks that result in a change in the state of motion of an object.
6) Can these terms (picking, opening, shutting, kicking, hitting, lifting, flicking, pushing, pulling) be replaced with one or more terms?
Answer: These terms can be replaced with the single term "force."
7) What are some examples of familiar situations involving the motion of objects?
Answer: Examples of familiar situations involving the motion of objects include:
Moving a book placed on a table
Opening or shutting a door
Drawing a bucket of water from a well
A football player taking a penalty kick
A cricket ball hit by a batsman
Moving a loaded cart
8) How can you identify the action involved in each case as a push or a pull?
Answer: To identify the action involved in each case as a push or a pull, you need to determine whether you are applying force to move the object towards you (pull) or away from you (push).
9) What is a push or a pull on an object called in science?
Answer: A push or a pull on an object is called a force in science.
10) What causes the motion of objects?
Answer: The motion of objects is caused by the action of a force.
11) When does a force come into play?
Answer: A force comes into play when there is a push or a pull on an object.
12) Is attraction a pull? What about repulsion between similar poles of two magnets? Is it a pull or a push?
Answer: Yes, attraction is a pull. Repulsion between similar poles of two magnets is also a push.
13) What happens when forces are applied on an object in the same direction?
Answer: When forces are applied on an object in the same direction, they add to one another.
14) What happens when forces are applied on an object in opposite directions?
Answer: When forces are applied on an object in opposite directions, they subtract from one another.
15) Under what condition is the net force on an object zero?
Answer: The net force on an object is zero if the two forces acting on it in opposite directions are equal.
16) What is the relationship between the direction of the applied force and its effect?
Answer: The direction of the applied force determines the direction of the object's motion.
17) What is the meaning of the net force being zero on an object?
Answer: The net force on an object is zero if the two forces acting on it in opposite directions are equal. This means that the object will not move or change its direction of motion.
18) What additional observation was made regarding tug-of-war?
Answer: The additional observation regarding tug-of-war was that if two teams pull with equal force, the rope does not move. This suggests that the net force on the rope is zero when the forces are equal and opposite.
19) What can we conclude about the relationship between forces and their effects on an object?
Answer: We can conclude that the strength and direction of a force determine its effect on an object. Forces can add or subtract depending on their direction. A net force of zero results when two equal and opposite forces act on an object.
20) What happens when a force is applied to a stationary ball?
Answer: When a force is applied to a stationary ball, it begins to move.
21) How does applying a force in the direction of a moving ball affect its speed?
Answer: Pushing a moving ball in the direction of its motion increases its speed.
22) What happens when a force is applied in the opposite direction of a moving ball?
Answer: Pushing a moving ball in the opposite direction of its motion decreases its speed.
23) What is the effect of placing your palm in front of a moving ball?
Answer: Placing your palm in front of a moving ball applies a force on it, causing it to slow down or stop.
24) What happens to the direction of motion of the ball when it strikes the ruler?
Answer: The direction of motion of the ball can change when it strikes the ruler, depending on the angle at which the ruler is placed.
25) Does the application of a force always result in a change in the state of motion of an object?
Answer: No, the application of a force does not always result in a change in the state of motion of an object. For example, a heavy box may not move even if you apply a large force.
26) What happens when you apply force on an inflated balloon by pressing it between your palms?
Answer: When you apply force on an inflated balloon by pressing it between your palms, the balloon's shape changes.
27) What happens to the shape of a ball of dough when it is rolled to make a chapati?
Answer: When you roll a ball of dough to make a chapati, its shape changes from a sphere to a flat circle.
28) What happens when you press a rubber ball placed on a table?
Answer: When you press a rubber ball placed on a table, its shape changes slightly.
29) What happens when you apply a force on an object that is free to move?
Answer: When you apply a force on an object that is free to move, it can cause the object to move, change its speed, or change its direction of motion.
30) What is the force resulting from the action of muscles called?
Answer: The force resulting from the action of muscles is called muscular force.
31) Can you perform activities involving movement or bending of your body without using muscular force?
Answer: No, you cannot perform activities involving movement or bending of your body without using muscular force.
32) Can animals perform their physical activities without using muscular force?
Answer: No, animals cannot perform their physical activities without using muscular force.
33) What is the difference between contact forces and non-contact forces?
Answer: Contact forces are forces that require physical contact between two objects, while non-contact forces can act on objects from a distance.
34) What happens to the magnet on the rollers when another magnet is brought near it?
Answer: When another magnet is brought near it, the magnet on the rollers may begin to move.
35) Does the magnet always move in the direction of the approaching magnet?
Answer: Yes, the magnet always moves in the direction of the approaching magnet.
36) What type of force acting between the two magnets?
Answer: The force acting between the two magnets is a non-contact force.
37) What is an electrostatic charge?
Answer: An electrostatic charge is a property acquired by an object after it has been rubbed with another object.
38) How can you observe the electrostatic force between two straws?
Answer: You can observe the electrostatic force between two straws by rubbing them with a sheet of paper and then bringing them near each other.
39) What happens when you bring the rubbed end of a straw near the free end of a suspended straw?
Answer: When you bring the rubbed end of a straw near the free end of a suspended straw, the suspended straw will either be attracted or repelled, depending on the charges of the two straws.
40) What is the nature of electrostatic force?
Answer: The electrostatic force is a non-contact force that can be either attractive or repulsive. It acts on charged bodies, even when they are not in contact.
41) What is the force that causes objects to fall towards the earth?
Answer: The force that causes objects to fall towards the earth is called gravity.
42) How does the area over which the force is applied affect the ease of a task?
Answer: The area over which the force is applied plays a role in making tasks easier. For example, it is easier to push a nail into a wooden plank with the pointed end than with the head.
43) What is pressure?
Answer: Pressure is the force acting on a unit area of a surface.
44) What is the formula for calculating pressure?
Answer: The formula for calculating pressure is: Pressure = Force / Area.
45) Why do porters place a round piece of cloth on their heads when they carry heavy loads?
Answer: Porters place a round piece of cloth on their heads when they carry heavy loads to increase the area of contact between the load and their heads. This reduces the pressure on their head and makes it easier to carry the load.
46) What happens when you pour water into a glass tube with a rubber sheet stretched over one end?
Answer: When you pour water into a glass tube with a rubber sheet stretched over one end, the rubber sheet bulges out.
47) How does the height of the water column in the tube affect the bulge in the rubber sheet?
Answer: The height of the water column in the tube affects the bulge in the rubber sheet. As you pour more water, the bulge in the rubber sheet increases.
48) What happens when you fill a plastic bottle with water and cover the mouth of the glass tube with a rubber sheet?
Answer: When you fill a plastic bottle with water and cover the mouth of the glass tube with a rubber sheet, the rubber sheet bulges out.
49) Do liquid and gas exert pressure?
Answer: Yes, both liquids and gases exert pressure. The pressure exerted by a liquid or gas depends on the height of the column of the fluid.
50) What happens when you fill a cylindrical container with water and drill holes near the bottom?
Answer: When you fill a cylindrical container with water and drill holes near the bottom, water will flow out of the holes.
51) Why do you have to close the mouth of an inflated balloon to keep it inflated?
Answer: You have to close the mouth of an inflated balloon to keep it inflated because gases exert pressure on the walls of their containers.
52) What happens when you open the mouth of an inflated balloon?
Answer: When you open the mouth of an inflated balloon, the air inside escapes due to the pressure difference between the inside and outside of the balloon.
53) Would you be able to inflate a balloon with holes?
Answer: No, you would not be able to inflate a balloon with holes because the air would leak out through the holes, preventing the balloon from inflating.
54) What is the atmosphere?
Answer: The atmosphere is the envelope of air that surrounds the Earth.
55) What is atmospheric pressure?
Answer: Atmospheric pressure is the pressure exerted by the atmosphere on the Earth's surface.
56) What happens when you press a rubber sucker hard on a smooth surface?
Answer: When you press a rubber sucker hard on a smooth surface, most of the air between the sucker and the surface escapes.
57) Why does the rubber sucker stick to the surface?
Answer: The rubber sucker sticks to the surface because the atmospheric pressure acting on the outside of the sucker is greater than the pressure inside the sucker.
58) What would happen to the rubber sucker if there were no air between the sucker and the surface?
Answer: If there were no air between the sucker and the surface, the rubber sucker would not stick to the surface.
59) How can you calculate the force exerted by air on your head?
Answer: You can calculate the force exerted by air on your head by using the formula: Force = Pressure x Area.
60) What is the force exerted by air on a column of air 15 cm x 15 cm in area and the height of the atmosphere?
Answer: The force exerted by air on a column of air 15 cm x 15 cm in area and the height of the atmosphere is nearly equal to the force of gravity on an object of mass 225 kg (2250N).
61) Why are we not crushed under the force of atmospheric pressure?
Answer: We are not crushed under the force of atmospheric pressure because the pressure inside our bodies is also equal to the atmospheric pressure, balancing the pressure from outside.
