A block of mass 10 kg, moving in x direction with a constant speed of 10 m s^$$-$$1, is subjected to a retarding force F = 0.1x J/m during its travel from x = 20 m to 30 m. Its final KE will be

One coolie takes 1 minute to raise a suitcase through a height of 2 m but the second coolie takes 30 s to raise the same suitcase to the same height. The powers of two coolies are in the ratio

A particle with total energy E is moving in a potential energy region U(x). Motion of the particle is restricted to the region when

A uniform force of $$\left( {3\widehat i + \widehat j} \right)$$ newton acts on a particle of mass 2 kg. Hence the particle is displaced from position $$\left( {2\widehat i + \widehat k} \right)$$ metre to position $$\left( {4\widehat i + 3\widehat j - \widehat k} \right)$$ metre. The work done by the force on the particle is