Question

If a `2 kg` object is constantly accelerated from `0m/s` to `15 m/s` over `12s`, how much power musy be applied at `t= 5`?

Answer 1

For constant acceleration happened,we can apply `v=u+at`(all the symbols are bearing their conventional meaning)

Given, `u=0,v=15,t=12`

so, `a= 15/12 m/s^2`

So,force acting(`F`) on the object is `(2*15/12) N` or, `15/6 N` (using `F=ma`)

Now, power = Work done per unit time = `(F*s)/t` (`s` is the displacement in time `t`)

So,displacement at `t=5` was
`(1/2)(15/12) (5^2 ) m` (using `s=1/2at^2`)

So,power at `t=5` was `(15/6 *(1/2)(15/12) (5^2 )) /5 W` i.e `7.81 W`