Work

Q.

Define work.

Q. What happens when an ebonite rod is rubbed with wool?

1. Only ebonite rod acquires charge.
2. Both, ebonite rod and wool, acquire opposite charges
3. Both, ebonite rod and wool, acquire similar charges
4. Neither the ebonite rod, nor the wool, acquire any charge.

Q.

A body is acted upon by a force that is inversely proportional to the displacement covered s. The work done will be proportional to:

1. s

2. s²

3. $\sqrt{s}$

4. none of the above

Q.

Write the expression for work done by a force.

Q.

Calculate the work done in lifting 200kg of water through a vertical height 6meters

Q. Question 5
A girl is carrying a school bag 3 kg on her back and moves 200 m on a leveled road. The work done against the gravitational force will be $(g=10m{s}^{-2})$

(a) $6\times {10}^3$ J
(b) 6 J
(c) 0.6 J
(d) zero

Q.

Question 16
The weight of a person on a planet A is about half that on the earth. He can jump upto 0.4 m height on the surface of the earth. How high he can jump on the planet A?

Q.

There are two mutually perpendicular forces acting on an object. One force acts in the direction of motion of the object and the direction of other force is perpendicular to the motion. During an interval the kinetic energy of the body changes from 25 J to 100 J. The work done by the force acting perpendicular to the direction of object is 0.

1. True

2. False

Q. Work done is the product of force and and it acts in the direction of the applied force .

1. momentum
2. velocity
3. displacement

Q. ntThe rate of doing work by force acting on a particle moving along x-axis depends on position x of particle and is equal to 2x . The velocity of particle is given by expression ?n

Q.

A force of $5N$ is acting on an object. The object is displaced through $2m$ in the direction of force. If the force acts on the object throughout the displacement. Find the work done by the force.

Q.

A force of 30 N acts on a body and moves it through a distance of 5m in the direction of force. Calculate the work done by the force.

Q. What are the factors affecting the amount of work done

Q.

A coolie is moving on a road with a luggage on his head. Does he perform work against the force of gravity? give reasons for your answer.

Q.

State two conditions when no work is done by a force.

Q.

(a) Work is said to be done by a force only when _________

(b) Work done = Force $\times$ _________

(c) The energy of a body is its capacity to do ______

(d) The S.I. unit of energy is ______

(e) The potential energy of a body is due to its ______ and kinetic energy of body is due to its ______

(f) Gravitational potential energy U = mass $\times$ force of gravity on unit mass $\times$ _________

(g) Kinetic energy = $\frac{1}{2}\times mass\times$_________

(h) Power P = ______ / time taken.

(i) The S. I. unit of power is ______

(j) 1 H.P. = ______ W

Q.

State two factors on which the work done on a body depends.

Q.

A coolie is moving on a road with a luggage on his head. Does he perform work against the force of gravity? Give reason for your answer.

Q.

It takes 20 s for girl A to climb up the stairs while girl B takes 15 s for the same job. Compare : (i) the work done and (ii) the power spent by them.

Q.

Write true or false for each statement:

(a) A coolie does not work against the force of gravity while carrying a luggage on a plane road.

(b) The energy stored in water of a dam is kinetic energy.

(c) The energy of a flying kite is kinetic energy.

(d) Work done by a boy depends on the time in which he does work.

(e) Power spent by a bosy depends on the time for which it does work.

Q.

A moon is revolving around the earth in a circular path. How much work is done by moon

Q.

An object of mass $1kg$ is at rest. A constant force of $10N$ is applied on it for 2 seconds. Find the work done by the force on the object.

1. $200J$
2. $20J$
3. $16J$
4. $180J$

Q. A force of $10N$ is applied on an object of mass $1kg$ for $2s$, which was initially at rest. What is the work done on the object by the force?

1. $160J$
2. $200J$
3. $160J$
4. $240J$

Q.

Give reasons for the following :

(a) No work is done if a man is pushing against a wall.

(b) The hammer drives a nail into the wood only when it is lifted up and then struck.

(c) A horse and a dog are running at the same speed. Which one of them has more kinetic energy than the other

(d) A teacher moving around in the class is doing work but a child standing and reading a book is not doing any work?

Q.

A body of mass mis moved from ground to a height h. If gorce of gravity on mass of 1 kg is g newton, find : (a) the force needed to lift the body, (b) the work done in lifting the body and (c) the potential energy stored in the body.

Q.

If there is no displacement then there is no work.

So when earth revolves around the sun it comes back to its position......... So will it be a work in physics

Q. A steel wheel of 600 mm diameter rolls on a horizontal steel rail. It carries a load of 500 N. The coefficient of rolling resistance is 0.3 . The force in N, necessary to roll the wheel along the rail is

Q.

Tractor is pulling a trolley. Whether work is done or not? [1 MARKS]

Q.

Give reason for the following -

A boy is carrying a box on his head and standing ;is he doing any work? Give reason .

Q.

Which of the following define the work most accurately?
​
1. Work is the product of displacement and component of force in the direction of displacement.
2. Work is the product of force and displacement.
3. Work is the product of force and component of displacement in the direction of force.
4. Work is the product of distance and force applied.

1. 1 and 3

2. 2 and 4

3. 1, 2 and 3

4. All of these