Class 8 Science - Force and Pressure CBSE Worksheets Solutions

Q.1. Give one practical application of magnetic force.

The closing of door of refrigerator works on the application of magnetic forces.

Q.2. Explain why snowshoes stop you from sinking into the snow.

The snow shoes have large, flat soles so they exert less on the soft snow and stop the wearer from sinking into it.

Q.3. Which force can be used to gather iron pins scattered on the floor?

Magnetic force can be used to gather iron pins scattered on the floor.

Q.4. Write one example where force changes the speed of a moving object.

Speed of moving a rubber tire or a ring increases whenever it is pushed.

Q.5. What is meant by a non-contact force? Give an example.

A force that can be exerted by an object even from a distance is called a non-contact force. The force exerted by a magnet is an example of a non-contact force.

Q.6. What is meant by atmospheric pressure?

The atmospheric air extends up to many kilometers above the surface of the earth. The pressure exerted by this air is known as atmospheric pressure.

Q.7. Why do the shape and size of balloons change when filled with air or water?

The high pressure produced by the gas or water molecules on the walls of the balloon causes it to expand and get inflated.

Q.8. What is muscular force? Give one example.

The force resulting due to the action of muscles is known as the muscular force. Example: lifting a bucket of water.

Q.9. What is meant by gravitational force (or force of gravity)? Give one example.

Every object in the universe, whether small or large, exerts a force on every other object. This force is known as the gravitational force. Example: Water begins to flow towards the ground as soon as we open a tap.

Q.10. Explain why the walls of a dam are thicker near the bottom than at the top.

The walls of a dam are much thicker at the bottom than it is at the top. This is because the pressure of the water is much greater deeper down and the dam needs to be thick at the bottom so that it is strong enough to withstand this larger pressure.

Q.11. Explain why the frictional force is said to be a contact force.

The force of friction always acts on all the moving objects and its direction is always opposite to the direction of motion. Since the force of friction arises due to contact between surfaces, it is an example of a contact force.

Q.12. Explain why the tip of a sewing needle is sharp.

The tip of the sewing needle is sharp so that due to its sharp tip, the needle may put force on a very small area of the cloth, producing a large pressure sufficient to pierce the cloth being stitched.

Q.13. What do you understand by the state of Motion?

The state of motion of an object is described by its speed and direction of motion. The state of rest is considered to be the state of zero speed. An object may be at rest or in motion; both are its states of motion.

Q.14. Why does a plastic comb rub with dry hair attract tiny pieces of paper?

When a plastic comb is rubbed in dry hair, the comb gets electric charges by friction. And when this electrically charged comb is brought near tiny pieces of paper, it exerts an electrostatic force of attraction on them. Due to this electrostatic force, the tiny pieces of paper move towards the comb and stick to it.

Q.15. Explain why, when a person stands on a cushion, the depression is much more than when he lies down on it.

When a man stands on a cushion then only his two feet are in contact with the cushion. Due to this, the weight of man falls on a small area of cushion producing a large pressure. This large pressure causes a big depression in the cushion. On the other hand, when the same man is lying on the cushion, then his whole body is in contact with the cushion. In this case, the weight of man falls on a much larger area of the cushion producing much smaller pressure. And this smaller pressure produces very little depression in the cushion.