CHAPTER 8 Force

FORCE

KEY WORDS

force	catapult
muscular	exerted
elastic	friction
frictional	resist
gravitational	motion

Define the terms

1.   Force: A push or a pull applied to an object is called a force.

2.   Gravity: Gravity is the gravitational force exerted by the earth on all the objects.

3.   Friction: Friction is a type of force that stops a moving object. When two surfaces come in contact with each other, they exert force of friction on each other

Question And answers

Q-1Write effects of force. Give an example for each.

Ans: Effects of force

1.  Force can move an object.eg: A ball moves when kicked.

2.   Force can stop a moving object. Eg: A Cycle stops when brakes are applied.

3.  Force can change the direction of a moving object. Eg: The player hits the shuttle cock to change its direction.

4.   Force can change the shape of the object. Eg: clay moulding changes shape of the clay.

Q-2 State the significance gravitational force.

Ans: Gravitational force keeps us and other objects on the ground. Without gravity there cannot be life on earth as it also holds our atmosphere.

Give Reason

1.  Why it is difficult to walk on ice?

Ans: Friction is less on any smooth surface (like ice) that is why it is difficult to walk on ice.

2.  Why do we slip when we step on a banana peel?

Ans: The banana peel makes the surface smooth, thereby reducing the friction between our feet and the ground and making us fall.