Question

An electric toy car with a mass of `3 kg` is powered by a motor with a voltage of `4 V` and a current supply of `1 A`. How long will it take for the toy car to accelerate from rest to `4 m/s^2`?

Answer 1

The time is `=6s`

Explanation:

Voltage is `U=4V`

Current is `I=1A`

The power of the motor is

`P=UI=4*1=4W`

Velocity is `v=4ms^-1`

Mass is `m=3kg`

The kinetic energy of the car is

`KE=1/2mv^2=1/2*3*(4)^2=24J`

But,

`E=P*t`

The time is `t=(24)/4=6s`