Question

An electric toy car with a mass of `2 kg` is powered by a motor with a voltage of `1 V` and a current supply of `6 A`. How long will it take for the toy car to accelerate from rest to `6 m/s`?

Answer 1

The time is `=6s`

Explanation:

The power is

`P=UI`

The voltage is `U=1V`

The current is `I=6A`

The power is

`P=UI=1*6=6W`

The kinetic energy of the car is

`E=1/2mv^2`

The mass is `m=2kg`

The speed is `v=6ms^-1`

so,

`E=1/2*2*(6)^2=36J`

Let the time `=ts`

`E=Pt`

`t=E/P=36/6=6s`