Class: 8
SCIENCE
Chapter – 11
Force and Pressure
GENERAL INSTRUCTIONS:
1. Question answers and assignment are to be done in Science Practice Notebook /
ruled sheets.
2. The link to the NCERT chapter is given below.
http://ncertbooks.prashanthellina.com/class_8.Science.Science/11.pdf
INTRODUCTION:
Force is a push or a pull applied on an object.
A force arises due to the interaction between two objects.
Force acting on an object may cause a change in its state of motion or a change in its
shape.
Force can be a contact or a non contact force.
Force per unit area is called pressure.
Liquids and gases exert pressure on the walls of their containers.
The pressure exerted by air around us is known as atmospheric pressure.
EXPLANATION:
FORCE: A push or a pull that changes or tends to change the state of rest or of uniform
motion of an object or changes its direction or shape.
A force arises due to the interaction between two objects. Force has magnitude as well as
direction.
The SI unit of force is newton.
Effect of Force:-
1. Force can change the state of motion: An Object can be in two states.
(a) Rest State: When an object is not moving. This means, a stationary object is said to be in
the state of rest. For example –A ball and book kept over the ground and not moving.
(b) Motion State: A moving object is said to be in the state of motion. For example – a
moving car, a moving ball, etc.
A Force can move a stationary object. A force can speed up, decrease the speed and change
the direction of a moving object. Force can stop a moving object. Finally, we can say that
force can change the state of motion.
Some examples:
(i) A boy wants to move a tyre faster, it has to be pushed repeatedly.
, (ii) Change in the direction of a moving ball after it strikes the ruler placed in its path.,
(iii) In the Football game, a goalkeeper stops the football going towards the goal post
by applying a force by his hands.
(iv) In the cricket game, a batsman can push a fast moving ball in the same direction or
opposite direction or change the direction of the movement of ball, because of force
being applied from his bat.
2. Force can change the shape of an object:
(i) When you apply force on an inflated balloon by pressing it using your hand from both
sides, then the force changes the shape of balloon.
(ii) You can change the shape of rubber band and spring by stretching it in opposite direction.
SCIENCE
Chapter – 11
Force and Pressure
GENERAL INSTRUCTIONS:
1. Question answers and assignment are to be done in Science Practice Notebook /
ruled sheets.
2. The link to the NCERT chapter is given below.
http://ncertbooks.prashanthellina.com/class_8.Science.Science/11.pdf
INTRODUCTION:
Force is a push or a pull applied on an object.
A force arises due to the interaction between two objects.
Force acting on an object may cause a change in its state of motion or a change in its
shape.
Force can be a contact or a non contact force.
Force per unit area is called pressure.
Liquids and gases exert pressure on the walls of their containers.
The pressure exerted by air around us is known as atmospheric pressure.
EXPLANATION:
FORCE: A push or a pull that changes or tends to change the state of rest or of uniform
motion of an object or changes its direction or shape.
A force arises due to the interaction between two objects. Force has magnitude as well as
direction.
The SI unit of force is newton.
Effect of Force:-
1. Force can change the state of motion: An Object can be in two states.
(a) Rest State: When an object is not moving. This means, a stationary object is said to be in
the state of rest. For example –A ball and book kept over the ground and not moving.
(b) Motion State: A moving object is said to be in the state of motion. For example – a
moving car, a moving ball, etc.
A Force can move a stationary object. A force can speed up, decrease the speed and change
the direction of a moving object. Force can stop a moving object. Finally, we can say that
force can change the state of motion.
Some examples:
(i) A boy wants to move a tyre faster, it has to be pushed repeatedly.
, (ii) Change in the direction of a moving ball after it strikes the ruler placed in its path.,
(iii) In the Football game, a goalkeeper stops the football going towards the goal post
by applying a force by his hands.
(iv) In the cricket game, a batsman can push a fast moving ball in the same direction or
opposite direction or change the direction of the movement of ball, because of force
being applied from his bat.
2. Force can change the shape of an object:
(i) When you apply force on an inflated balloon by pressing it using your hand from both
sides, then the force changes the shape of balloon.
(ii) You can change the shape of rubber band and spring by stretching it in opposite direction.
