Work done in time t on a body of mass m which is accelerated from rest to a speed v in time t1 as a function of time t is given by
`1/2` m `v/t_1` t2
m `v/t_1` t2
`1/2` `((mv)/t_1)^2` t2
`1/2` m `v^2/(t_1^2)` t2
how?