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CBSE Sample Paper Class 8 Science Force and Pressure
1.) Answer the short questions (10×1)
a.) What is force??
b.) What happens when we use force in the same direction?
c.) Give an example of forces applied in different direction.
d.) What is muscular force?
e.) What is contact force?
f.) Strength of force is expressed by which unit?
g.) Give an example of non-contact force.
h.) What is electrostatic force?
i.) What is pressure?
j.) What is atmospheric pressure?
2.) Briefly answer the following questions (5×3)
a.) Describe how force may bring a change in the state of motion of an object.
b.) Describe state of motion.
c.) Mention the changes may occur during after application of force on an object.
d.) Explain friction with suitable example.
e.) Describe force of gravity with examples.
3.) Fill in the blanks (10×1)
a.) Muscular force is also known as _______ force.
b.) A ball rolling on the surface gradually slowing down is an example of ______ .
c.) _______ is usually used to express the strength of a force.
d.) Stopping a running ball makes its speed ______ .
e.) Iron attracted by magnet is an example of _______ force.
f.) Paper rubbed plastic straw attracting another normal plastic straw is an example of _______ force.
g.) Pressure= ______ / ______ .
h.) If kept in a container ______ and _____ both exert pressure on the walls of the container.
i.) The envelope of air around us is known as ________ .
j.) Force can be ______ or _______ .
4.) Write true or false (15×1)
a.) Force can be a push or pull.
b.) If we pull a car from behind it’s speed would increase.
c.) Stopping any moving object increases its force of speed.
d.) Change in the speed or direction causes it’s change in its state of motion.
e.) Pressure exerted by air around us is known as physical pressure.
f.) Force applied on an object can change its shape.
g.) Gravity is only available in Earth.
h.) If we push an non-moving object it will increase its speed.
i.) Pressure is equal to force/area.
j.) Gravitational force keeps us attached to the Earth.
k.) Only humans use muscular force.
l.) If we roll a ball it will keep rolling without slowing down.
m.) Magnetic attraction is a contact force.
n.) Charged body exerts electrostatic force.
o.) Liquid exerts pressure on the walls of container.
Answer
1.) Answer the short questions (10×1)
a.) What is force??
Answer – Motion impaired to an object due to either push or pull is called force.
b.) What happens when we use force in the same direction?
Answer –If we use force in the same direction add to one another. This will increase the state of motion of the object.
c.) Give an example of forces applied in different direction.
Answer –“Tug of war” is an example of forces applied in different direction.
d.) What is muscular force?
Answer –Muscular force is a type of force which results from the action of muscles.
e.) What is contact force?
Answer – Contact force is a type is force which can be applied only with the contact with the object.
f.) Strength of force is expressed by which unit?
Answer – Strength of force is expressed by unit called Magnitude.
g.) Give an example of non-contact force.
Answer – Magnetic attraction is an example of non-contact force.
h.) What is electrostatic force?
Answer – Electrostatic force is a type of force which is excited by a charged object to an uncharged or charged object.
i.) What is pressure?
Answer – Pressure is an unit which is defined as force per unit area.
j.) What is atmospheric pressure?
Answer – A gas envelope around us is called atmosphere.This atmosphere exerts pressure. This pressure is called atmospheric pressure.
2.) Briefly answer the following questions (5×3)
a.) Describe how force may bring a change in the state of motion of an object.
Answer –Force can be either push or pull. But force can bring changes in the state of motion of an object. This changes can be,
- Force can increase the speed of an object.
For example, when a football player taking a penalty kick the ball is in a non moving state and the speed is zero. When the player hits the ball it increases the speed of the ball.
- Force can decrease the speed of an object.
For example, if goalkeeper stops the ball hit by player the speed of the ball decreases.
- Force change the direction of an object.
For example, in a cricket match the batsman applies forced to change the direction of the ball to score.
b.) Describe state of motion.
Answer –State of motion of an object is described by the speed and direction of the object.State of motion are two types,
A.) State of rest
B.) State in motion
The state of rest can be changed into state in motion by the application of force. Force can change the state of motion of an object by various methods.
c.) Mention the changes may occur during after application of force on an object.
Answer – The changes may occur during application of force on an object can be,
- Force can change the shape of an object.
- Force can decrease the speed of an object.
- Force can increase the speed of an object.
- Force can change the direction of an object.
d.) Explain friction with suitable example.
Answer –Friction is one type of force, friction changes the state of motion of an object.
For example, if we roll a ball on the surface it will roll for a bit and stop rolling after sometime. This is due to the friction between the ball and the surface
e.) Describe force of gravity with examples.
Answer –The force of gravity is an attractive force. It’s applied on all the objects around us. If we throw a stone towards the sky it falls because the gravitational force of Earth pulls them.
Some examples of gravitational force are,
- Water flowing downwards.
- Leaves falling form the trees.
3.) Fill in the blanks (10×1)
a.) Muscular force is also known as contact
b.) A ball rolling on the surface gradually slowing down is an example of friction .
c.) Magnitude is usually used to express the strength of a force.
d.) Stopping a running ball makes its speed zero .
e.) Iron attracted by magnet is an example of non-contact
f.) Paper rubbed plastic straw attracting another normal plastic straw is an example of electrostatic
g.) Pressure= force / area .
h.) If kept in a container gas and liquid both exert pressure on the walls of the container.
i.) The envelope of air around us is known as atmosphere .
j.) Force can be push or pull.
4.) Write true or false (15×1)
a.) Force can be a push or pull.
Answer –True
b.) If we pull a car from behind it’s speed would increase.
Answer –False
c.) Stopping any moving object increases its force of speed.
Answer –False
d.) Change in the speed or direction causes it’s change in its state of motion.
Answer – True
e.) Pressure exerted by air around us is known as physical pressure.
Answer – False
f.) Force applied on an object can change its shape.
Answer – True
g.) Gravity is only available in Earth.
Answer – False
h.) If we push an non-moving object it will increase its speed.
Answer – True
i.) Pressure is equal to force/area.
Answer – True
j.) Gravitational force keeps us attached to the Earth.
Answer – True
k.) Only humans use muscular force.
Answer – False
l.) If we roll a ball it will keep rolling without slowing down.
Answer – False
m.) Magnetic attraction is a contact force.
Answer – False
n.) Charged body exerts electrostatic force.
Answer – True
o.) Liquid exerts pressure on the walls of container.
Answer – True