Question

If a `12 kg` object is constantly accelerated from `0m/s` to `40 m/s` over 18 s, how much power musy be applied at `t=1`?

Answer 1

`29.61 W`

Explanation:

Force acting on the mass is `F=ma=(m(v-u))/t=(12(40-0))/18=26.67N` (where, `v` is the final velocity and `u` is the initial velocity)

Now,at `t=1` displacement was `s=0+1/2 (40/18) 1^2=1.11m`

So,work done after `1s` is `Fs=26.67*1.11=29.61J`

So,power applied = work done per unit time =`29.61/1=29.61W`