How much work does a boy of mass 50kg do when he climbs a height 30 metre.

How much work is done on a body of mass m in moving it around a horizontal circle of radius R?

What is gravitational potential energy at a point? How much of work is done in shifting mass from the surface to a height equal to its radius?

Work Problem on Time and Work Nine boys and four girls complete a piece of work in four days. Two boys and four girls complete that work in ten days. How much time does a boy or a girl alone need to complete the work.

A boy standing on a stationary lift (open from above) throws a ball upwards with the maximum initial speed he can, equal to 49 m/s. How much time does the bail take to return to his hands? If the lift starts moving up with a uniform speed of 5 m/s and the boy again throws the ball up with the maximum speed he can, how long does the ball take to return to his hands?

How much work is done when a charge q moves over an equipotential surface?

How does a gas do work when its expands adiabatically ?

:A 10 kW drilling machine is used to drill a bore in a small aluminium block of mass 8.0 kg. How much is the rise in temperature of the block in 2.5 minutes, assuming 50% of power is used up in heating the machine itself or lost to the surroundings. Specific heat of aluminium = 0.91 J g^-1 K^-1 .

A person trying to lose weight (dieter) lifts a 10 kg mass, one , thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the mass is dissipated, (a) How much work does she do against the gravitational force? (b) Fat supplies 3.8 xx 10^7 J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?

How much momentum will a dumb-bell of mass 10 kg transfer to the floor if it falls from a height of 80 cm? Take its downward acceleration to be 10 ms^-2 .

With what velocity a body has to be thrown up so that it can rise up to a height of 10 metres from the ground? How much time will fake to reach the highest point?