A particle moves along a circle of radius $$\left( {{{20} \over \pi }} \right)$$ m with constants tangential acceleration. If the velocity of vthe particle is 80 m/s at the end of the second revoluation after motion has begun, the tangential acceleration is

When a long spring is stretched by 2 cm, its potential energy is U. If the spring is stretched by 10 cm, the potential energy stored in it will be

A child is sitting on a swing. Its minimum and maximum heights from the ground 0.75 m and 2 m respectively, its maximum speed will be

Two springs A and B having spring constant K_A and K_B (K_A = 2K_B) are stretched by applying force of equal magnitude. If energy stored in spring A is E_A then energy stored in B will be