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प्रश्न
A coolie, with a load of 30 kg on his head, walks on the platform. If he walks a distance of 60 m, what is the work done by him?
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उत्तर
The work done by the coolie is zero because there is no displacement of’ the load in the direction of force, which he is applying vertically upwards.
संबंधित प्रश्न
A force acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of the force. What should be the value of θ to get the maximum positive work?
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)
A cricket ball is thrown up from the earth's surface. What happens to its P.E.
(a) during the motion
(b) at the highest point?
A canon ball of mass 500g is fired with a speed of 15m/s-1. Find: its momentum.
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.
A force can cause an object to change its ______.
