Effects of Force

Question 1 Give examples where force moves a stationary object?

Question 2  Give examples where force stops a moving object?

Question 3 Give examples where force can change the speed of moving object?

Question 4 Give examples where force can change the direction of moving object?

Question 5 Give examples where force can change the shape and size of an object?

Question 6 Why does the shape of tooth paste tube changes when we squeeze it?

Question 7 What happens to the springs of a sofa when we sit on it?

A force can produce the following effects:

(1) A force can move a stationary object

(2) A force can stop a moving object

(3) A force can change the speed of a moving object

(4) A force can change the direction of a moving object

(5) A force can change the shape and size of an object

A Force can move a Stationary Object

(1) Take a rubber ball and place it on table top. Now gently push the ball along the surface of table, the ball begins to move. Thus a ball at rest begins to move when a force is applied to it.

(2) If we kick a stationary football kept on the ground, then the football starts moving. The force of our foot makes the stationary football to move.

(3) The force of engine makes a stationery car to move.

A Force can stop a Moving Object

(1) Take a rubber ball and place it on a table. Push the rubber ball gently so that it starts moving. Place your palm in front of the moving ball. We will observe that moving ball comes to a stop. The palm held in the path of moving rubber ball applies a force to the moving ball.

(2) The stopping of a moving football by a goalkeeper demonstrates that a force can stop a moving object.

(3) A cricket ball moving on the ground stops automatically after some time. The force of friction of ground stops the moving cricket ball.

(4) The force of brakes can stop a moving car.

A Force can change the Speed of Moving Object

(1) Suppose we are moving a bicycle at a certain speed. Now if someone pushes the moving bicycle from behind ,then the speed of bicycle increases and it will move faster. If someone pulls the moving  bicycle from behind then the speed of bicycle decreases and it will move slower.

A push or pull can change the speed of a moving bicycle. If the force is applied in the direction of motion of the object, its speed increases. If the force is applied in the direction opposite to the direction of motion of an object then its speed decreases.

(2) When a ball is dropped from a height its speed goes on increasing because the earth applies a pulling force on it which is called force of gravity. When a ball is thrown upward, then its speed goes on decreasing because the earth applies a pulling force of gravity on the ball in the downward direction that is opposite to the motion of the ball.

(3) When a hockey player hits a moving ball, the speed of ball increases.

(4) When we pedal the bicycle faster, then the speed of bicycle increases and when we apply brakes to the moving bicycle then the speed of bicycle decreases.

A Force can change the Direction of a Moving Object

(1) In a cricket match, when a moving cricket ball is hit by a bat ,then the direction cricket ball changes and it goes in another direction. The force exerted by bat changes the direction of moving cricket ball.

(2) In the game of carrom ,when we take a rebound then the direction of striker changes because the edge of the carrom board exerts a force on the strike.

(3) If we blow air from from our mouth on the smoke rising up from burning Agarbatti then the direction of motion of smoke changes. The force exerted by the blowing air changes the direction of moving smoke.

A change in either the speed of an object, or the direction of its motion, or both, is called change in its state motion.

A force can change the Shape and Size of an Object

(1) If we take a spring and pull it at both the ends with our hands ,then the shape and size of the spring changes, the force of our hands changes the shape and size of the spring.

(2) The shape of dough changes on pressing with rolling pin to make chapatis. When we press the dough with a rolling pin, we apply force.

(3) The shape of kneaded wet clay changes when a Potter converts it into pots of different shapes and sizes because the Potter applies force on the kneaded wet clay.

(4) The shape of toothpaste tube changes when we squeeze it because we apply force while squeezing it.

(5) When we hammer a piece of aluminium metal its shape changes and aluminium sheet is formed .

(6) When we sit on a sofa with Springs, then the springs of the sofa get compressed and their shape and size changes. Because our weight applies a force on the spring and compress them. The shape and size of a balloon changes when it is filled with air because weight of air exerts a force on the walls of balloon from inside.