How much wok is done in lifting a body of mass `60kg` and relative density `3` lying in the bed of a lake of depth `5m`

Four men light a 250 kg box to a height of 1m and hold it without raising or lowering it. (a) How much work is done by the men in lifting the box ? (b) How much work do they do in just holding it ? (c ) why do they get tired while holding it ? (g = 10m//s^2)

A pump is required to lift 1000kg of water per minute from a well 20m deep and eject it at a rate of 20ms^-1 . a. How much work is done in lifting water? b. How much work is done in giving in KE? c. What HP(horsepower) engine is required for the purpose of lifting water?

Calculate the mass of a body whose volume is 2 m^3 and relative density is 0.52

How much work is needed to be done on a ball of mas 50 g to give it a momentum of 5 kg m s^(-1) ?

In the figure shown the man of mass 60kg is liftinga block of mass 10kg with an acceleration of 5m//s^(2) . Find reading of the machine.

How much a body of mass 60 kg weight at (i) the pole, (ii) the equator and (iii) a latitude of 30^(@) ? Radius of earth is 6371km.

A silver block of mass 3.1 kg is connected to a string and is then immersed in a liquid of relative density 0.82 . Find the tension in the string , if relative density of silver is 10.5

What is the decrease in weight of a body of mass 800 kg when it is taken into a mine of depth 1500m? Radius of the earth is 6371km.

A pump is required to lift 1000kg of water per minute from a well 12m deep and eject it with a speed of 20ms^-1 . How much work is done per minute in lifting the water and what must be the power output of the pump?

How much force is applied on the body when 780 J of work is done in displacing the body through a distance of 30 m in the direction of force?