# CBSE – 8th Standard Science ## CBSE – 8th Standard Science

### Question Bank – Chapter 11 – Force and Pressure

Chapter 11

Force and Pressure

Q1 Define Force?

Ans. Actions usually results in some kind of change in the motion of an object.  A push or a pull on an object is called a force.

Q2. What makes an object to direction of motion?

Ans. An interaction of one object with another object results in a force between the two objects.

Q3. What happens when two forces act in opposite direction on an object?

Ans. If the two forces act in the opposite directions on an object ,it could be zero or  the net force acting on it is the difference between the two forces.

Q4. What is the unit to measure force?

Ans. The strength of a force is usually expressed by its magnitude as force could be larger or smaller than the other.

Q5. State all changes due to force ?

Ans. The force make an object move from rest it may change the speed of an object if it is moving, it may change the direction of motion  and  may bring about a change in the shape of an object.

Q6. What are the States of motion?

Ans. The state of motion of an object are speed and the direction ,an object may be at rest or in motion; both are its states of motion.

Q7. Name some Contact and Non contact forces.

Ans. Muscular force and friction are contact forces while Magnetic, Electrostatic and Gravitational forces are non contact forces.

Q8. Give examples in which you push or pull to change the state of motion of objects.

Ans.  We push while Picking ,balling  and lifting  but  game tug of war , movement of bullock cart is because of pulling force.

Q9. Give two examples in which applied force causes a change in the shape of an object.

Ans.  Making chapatti and stretching on rubber band causes a change in the shape of objects.

Q10. Name two forces acting on the rocket immediately after leaving the launching pad.

Ans. Gravitational Force and friction of atmospheric pressure both act on a leaving rocket.

Q11. What force helps our body to do activity?

Ans. It is the muscular force that enables us to perform all activities involving movement or bending of our body.

Q12. Is there any relation between pressure and force?

Ans. The force acting on a unit area of a surface is called pressure. Pressure is equal to force per unit area on which it acts.

Q13. What is called atmospheric pressure?

Ans. The pressure exerted by air around us is known as atmospheric pressure, winds and cyclones are caused by the differences in air pressure.

Q14. What is reason we are not crushed by the Atmospheric pressure on our body?

Ans. The reason we are not crushed under this weight is that the pressure inside our bodies is also equal to atmospheric pressure and cancels the pressure from outside.

Q15. Is Gravity a property of only our Earth?

Ans. Gravity is not a property of the earth alone. In fact, every object in the universe, whether small or large, exerts a force on every other object.

Try these:-

What are the applications of atmospheric pressure of earth?

State whether the following statements are true or false :-

1. The unit of force is pascal.
2. Weight is measured in newton.
3. Pulling a cart needs direct contact with the object.
4. Direction in which an object is pushed or pulled is measure of magnitude of force.
5. Interaction between two objects always involve direct physical contact.

Why do astronauts appear floating inside a spaceship?