The speed of a cycle increases from 2.5 m/s to 5 m/s. The total mass of the cyclist including the cycle is 120 kg. Calculate the work done by the cyclist to increase the speed.
Use work-energy theorem, and write:
\(W=m(\Large\frac{ v ^{2}-u ^{2} }{ 2 })\) directly.
This is more general than the derivation provided by shamim, as it will be true even for non-uniform acceleration.
But this will only be true if the cyclist is on a horizontal road.