Question

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

Answer 1

Answer:

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

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 $\Delta\overrightarrow{v}$:

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

$\Delta\overrightarrow{v}=7.69\,\frac{m}{s}$