Work and Energy...

A force applied by an engine of a train of mass $$ 2.05 \times 10^6  \ kg $$  changes it velocity from $$ 5 \ m /s $$ to $$ 25\ m/s $$  in $$ 5\ minutes$$. The power of engine is 

A car of mass 1000 kg accelerates uniformly from rest to a velocity  of 54 km/hour in 5s. The average power of the engine during this period in watts is (neglect friction)

An electric lamp is marked $$60 \ W$$, $$230 \ V$$. The cost of $$1 \ kilowatt-hour$$ of power is $$Rs \ 1.25$$. The cost of using this lamp for $$8 \ hours$$ is

The power of pump, which can pump $$200 \ kg$$ of water to a height of $$50 \ m$$ in $$10 \ sec$$, will be

The spring will have maximum potential energy when 

Kilowatt hour is unit of

When spring is compressed its potential energy........

Masses of two bodies are $$1$$ kg and $$4$$ kg respectively. If their kinetic energies are in $$2:1$$ proportion, the ratio of their speeds is .........

Some children were trying to find out which of three bulbs was brightest. Which one of these gives the best start toward finding the answer?

Calculate the energy possessed by a stone of mass $$10\ kg$$ kept at a height of $$5\ m$$. 
Take $$g = 9.8\ m/s^{2}$$