Question

A constant friction force of 25 Nacts on a 65 kg skier for 20

s. Whatis the skier's change in velocity?

Answer 1

The skier's change in velocity is 7.69 meters per second.

Step-by-step explanation:

The Newton's second law tells force is equal to the change on the linear momentum of a body:

`\sum\overrightarrow{F}=\frac{d\overrightarrow{p}}{dt}`

If we approximate the differential
`\frac{d\overrightarrow{p}}{dt}` to
`\frac{\Delta\overrightarrow{p}}{\Delta t}`:

`\sum\overrightarrow{F}=\frac{\Delta\overrightarrow{p}}{\Delta t}`

Using that linear momentum is mass times velocity:

`\sum\overrightarrow{F}=\frac{m\Delta\overrightarrow{v}}{\Delta t}`

Solving for
`\Delta\overrightarrow{v}`:

`\Delta\overrightarrow{v}=\frac{\Delta t\sum\overrightarrow{F}}{m}=((20\,s)(25\,N))/(65\,kg)`

`\Delta\overrightarrow{v}=7.69\,(m)/(s)`