Question

How much work is required to increase the speed of a 8 kg cart from 2 m/s to 7 m/s?

Answer 1

180 J

Explanation:

To know the work required we must calculate the work at 7 m/s and at 2 m/s, the difference would be the work required.

The work done is the same as the amount of energy increase. The formula for kinetic energy is:

`(1)/(2)m\cdot v^2`

We calculate in each case:

`\begin{gathered} (1)/(2)\cdot8\cdot7^2=196\text{ J} \\ (1)/(2)\cdot8\cdot2^2=16\text{ J} \end{gathered}`

The difference between these is the amount of work done:

`W=196-16=180\text{ J}`

The work required is 180 J