Question

A toy car of mass 8 kg initially moves with a speed of 5 m/s. How much work must be done on the car to increase its speed to 10 m/s?

Answer 1

ANSWER:

300 J

STEP-BY-STEP EXPLANATION:

To know the work required, we must calculate the work in both cases, the difference would be the amount of work necessary for the speed to increase. The work done is the same as the amount of energy increase. The formula for kinetic energy is:

$\frac{1}{2}m\cdot v^2$

We calculate in each case:

$\begin{gathered} \frac{1}{2}\cdot8\cdot10^2=400\text{ J} \\ \frac{1}{2}\cdot8\cdot5^2=100\text{ J} \end{gathered}$

We calculate the difference between the two to find out the work required:

$400-100=300\text{ J}$

The work required is 300 J