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प्रश्न
Define work.
उत्तर १
The definition of work states that when force is applied on a body and the body moves then work is said to be done.
उत्तर २
An action in which one exerts a force to move an object is known as work.
संबंधित प्रश्न
Work done by a boy depends on the time in which he does work.
Work done = Force × ........................................
The S.I. unit of work is
In which of the following cases is work being done:
- A boy pushing a heavy rock
- A boy climbing up the stairs
- A coolie standing with a box on his head
- A girl moving on the road.
A force of 30 N acts on a body and moves it through a distance of 5 m in the direction of force. Calculate the work done by the force.
A body, when acted upon by a force of 10 kgf, moves to a distance 0.5 m in the direction of force. Find the work done by the force. Take 1 kgf = 10 N.
In which of the following cases, is work being done?
(i) A man pushing a wall.
(ii) a coolie standing with a load of 12 kgf on his head.
(iii) A boy climbing up a staircase.
1 J = ______ calorie.
.A man raises a box of mass 50kg to a height of 2m in 20s, while another man raises the same box to the same height in 50s. Compare:
(i) the work done, and
(ii) the power developed by them.
A vessel containing 50 kg of water is placed at a height 15 m above the ground. Assuming the gravitational potential energy at ground to be zero, what will be the gravitational potential energy of water in the vessel? (g = 10 m s-2)
Find the kinetic energy of a body of mass 1 kg moving with a uniform velocity of 10 m s-1.
A bullet of mass 0.5 kg slows down from a speed of 5 m s-1 to that of 3 m s-1. Calculate the change in kinetic energy of the ball.
What do you mean by degradation of energy?
Explain degradation of energy by taking two examples of your daily life.
A car is being driven by a force of 2.5 ✕ 1010 N. Travelling at a constant speed of 5 m/s, it takes 2 minutes to reach a certain place. Calculate the work done.
A force of 50 N acts on a body and moves it a distance of 4 m on horizontal surface. Calculate the work done if the direction of force is at an angle of 60° to the horizontal surface.
What should be the angle between the direction of force and the direction of motion of a body so that the work done is zero?
A max X goes to the top of a building by a vertical spiral staircase. Another man Y of the same mass goes to the top of the same building by a slanting ladder. Which of the two does more work against gravity and why?
A girl weighing 400 N climbs a vertical ladder. If the value of g be 10 m s−2, the work by her after climbing 2 m will be :
Determine the amount of work done when an object is displaced at an angle of 30° with respect to the direction of the applied force.
Why is the work done on an object moving with uniform circular motion zero?
A uniform circular motion is an accelerated motion. Justify it.
A boy does work when he pushes against a brick wall. (yes/no).
Write an expression for the work done against gravity.
Can every force produce work?
Complete the following sentences:
The SI unit of work is ....... and of power is .......
Complete the following sentences:
Joule is the unit of .......
A boy of mass m climbs up a staircase of vertical height h.
- What is the work done by the boy against the force of gravity?
- What would have been the work done if he uses a lift in climbing the same vertical height?
Can work done be zero even if force acts on the body?
A body does 20 J of work in 10 s. What is its power?
Calculate the amount of work done by a child carrying a bag of 20 kg when he moves a distance of 40 m in
(a) Vertical direction, and
(b) Horizontal direction
A block of mass 20 kg is pulled up a slope (fig.12) with a constant speed by applying a force of 500 N parallel to the slope. A and B are initial and final positions of the block.
(a) Calculate the work done by the force in moving the block from A and B.
(b) Calculate the potential energy gained by the block.
How much energy is gained by a box of mass 20 kg when a man, runs carrying the box with a speed of 3 m/s-1 to catch the bus?
In the following case write yes, if the work is being done and no if no work is being done.
A boy climbing up a staircase.
Explain, why submarines are able to dive underwater as well as a sail on the surface of the water?
If a ball is dropped on the sloping roof of a house, it acquires ______ and falls on the ground. That is the transformation of ______ energy into ______ energy takes place.
(kinetic, potential, motion)
One labourer carried four pans of road metal through a distance of 100 metres. If he carries two pans of road metal through a 200 metre distance ______ work will be done.
Look at the activity below. Reason out whether or not work is done in the light of your understanding of the term ‘work’.
An engine is pulling a train.
A proton is kept at rest. A positively charged particle is released from rest at a distance d in its field. Consider two experiments; one in which the charged particle is also a proton and in another, a positron. In the same time t, the work done on the two moving charged particles is ______.
State whether work is done or not, by writing yes or no, in the following case:
A man pushes a wall.
