# An electric toy car with a mass of #2 kg# is powered by a motor with a voltage of #4 V# and a current supply of #8 A#. How fast can the toy car accelerate from rest to #3 m/s#?

##### 1 Answer

Jun 28, 2016

The car will take

#### Explanation:

Voltage and current relate to power by the equation

Power in turn, relates to work by the equation

Kinetic energy is simply a measure of work and has the form

So in order to solve this, we first determine the power output of the motor. This is

Using this result and the second equation, we can rearrange terms to show that

Using the third equation and plugging in the given values, we can see that

The rest is trivial algebra. Using