Question

If a `2 kg` object is constantly accelerated from `0m/s` to `18 m/s` over `5 s`, how much power musy be applied at `t= 3`?

Answer 1

The power is `=77.76W`

Explanation:

The mass of the object is `m=2kg`

Use the equation of motion

`v=u+at`

To calculate the acceleration

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

The final velocity is `v=18ms^-1`

The time `t=5s`

The acceleration is

`a=(v-u)/t=(18-0)/5=3.6ms^-2`

According to Newton's Second Law of Motion, the force acting on the object is

`F=ma=2*3.6=7.2N`

The velocity at `t=3s` is

`v=0+3.6*3=10.8ms^-1`

The power is

`P=Fv=7.2*10.8=77.76W`