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प्रश्न
State the energy changes which take place when A toy car with a wound spring moves on ground.
उत्तर
P.E (Wound spring) to K.E. (motion)
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संबंधित प्रश्न
When do we say that work is done?
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
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.
State the S.I. unit of energy.
Give reasons for the following. No work is done if a man is pushing against a wall.
A boy of mass 40 kg climbs up the stairs and reaches the roof at a height 8 m in 5 s. Calculate:
- the force of gravity acting on the boy,
- the work done by him against the force of gravity,
- the power spent by boy. (Take g = 10 m s-2)
State the energy transformation on the following:
Electricity is obtained from solar energy.
Does the earth move around the sun with a uniform velocity?
A weight lifted a load of 200 kgf to a height of 2.5 m in 5 s. calculate: (i) the work done, and (ii) the power developed by him. Take g= 10 N kg-1.
An electric motor drives a machine which lifts a mass of 4 kg through a height of 10 m in 5 s at a constant speed. Assuming g = 10 ms-2, calculate
(i) the amount of work done, (ii) the power of the machine.
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.
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.
State the amount of work done by an object when it moves in a circular path for one complete rotation. Give a reason to justify your answer.
Why is less effort needed to lift a load over an inclined plane as compared to lifting the load directly?
A bucketful of water is to be drawn from a well ______ will be done when a ______ is applied to do this because there will be a ______ of water.
(displacement, work, force)
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.
A ______ should act on an object.
A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table?
State whether work is done or not, by writing yes or no, in the following case:
A man pushes a wall.
