Force

Q.

SI unit of force is kg m s^-2. This unit is also known as:

1. Joule

2. Watt

3. Kilowatt

4. Newton

Q.

Write an expression for the work done when a force acts on an object in the direction of its displacement.

Q.

What is the inertia of motion?

Q.

Is force a energy?

Q. When do we say that work is
done

Q. Force can change the direction of a moving object.

1. False
2. True

Q.

Why is it advised to tie any luggage kept on the roof of a bus with a rope?

Q. Is it possible that some force is acting on a body but still the work done it's zero

Q.

Give any two examples of work in your daily life?

Q.

A man pushes a wall and fails to displace it. He does

1. Negative work

2. Positive but not maximum work

3. No work at all

4. Maximum work

Q. Why do we lean forward when a train stops?

Q.

What is the condition for a force to do work on a body ?

Q.

Name the physical quantity whose SI unit is Newton

Q.

The mechanical advantage of an inclined plane is always

1. equal to one

2. greater than 1

3. cannot be determined

4. lesser than 1

Q.

1, What is work?

Q.

Why work done against the gravity is negative? [2 MARKS]

Q.

All the cars are provided with seat belts. Give reason.

Q.

Work done by a body is

1. negative, positive or zero

2. always positive

3. always negative

4. always zero

Q. Question 4
A batsman hits a cricket ball which then rolls on a level ground. After covering a short distance, the ball comes to rest. The ball slows to a stop because
(a) the batsman did not hit the ball hard enough.
(b) velocity is proportional to the force exerted on the ball.
(c) there is a force on the ball opposing the motion.
(d) there is no unbalanced force on the ball, so the ball would want to come to rest.

Q.

Define contact and non -contact forces. Give 3 examples of each.

Q. Calculate the resultant force acting on the block.

1. $\text{50 N}$ towards left
2. $\text{70 N}$ towards right
3. $\text{30 N}$ towards right
4. $\text{30 N}$ towards left

Q.

In order to get minimum work, the angle between force and displacement should be $90°$.

1. True
2. False

Q. Hydraulic machine's working is based on the Pascal's Law.

1. True
2. False

Q.

State the condition need to be satisfied for work to be done

Q. What do you mean by zero work, positive work and negative work?

Q. Force can change the direction of a moving object.

1. False
2. True

Q. Which of the following CAN NOT be a possible effect of a force acting on an object?

1. It can change the shape and size of the object.
2. It can change the direction of motion of the object.
3. It can change the material and colour of the object.
4. It can change the speed of the object.

Q. What force is aplied on a piston of area of cross section $2c{m}^2$ to obtain a force $150$N on the piston of area cross section $12c{m}^2$ in a hydraulic machine?

Q. Question 8
A water tanker filled up to $\frac{2}{3}$ of its height is moving with a uniform speed. On sudden application of the brake, the water in the tank would
(a) move backward
(b) move forward
(c) be unaffected
(d) rise upwards

Q.

Name the kind of force which acts on a football rolling down on a football ground.