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= 4`?

Answer 1

The power is `=12.5W`

Explanation:

Apply the equation

`v=u+at`

to calculate the acceleration

The initial velocity is `u=0ms^-1`

The final velocity is `v=15ms^-1`

The time is `t=12s`

The acceleration is

`a=(v-u)/(t)=(15-0)/(12)=1.25ms^-1`

According to Newton's Second Law

`F=ma`

The mass is `m=2kg`

The force is `F=2*1.25=2.5N`

The velocity at `t=4s` is

`v=0+1.25*4=5ms^-1`

The power is

`P=Fv=2.5*5=12.5W`