Question

A 2.5 kg otter starts from rest at the top of a
muddy incline 86.2 cm long and slides down
to the bottom in 0.50 s.
What net external force acts on the otter
along the incline?
Answer in units of N.

Answer 1

First of all, we determine the acceleration $a$ the otter descended. To do this, we write out the formula for uniformly accelerated motion $s=a\cdot \frac{t^2}{2}$ . From this formula we find the acceleration

$a=2\cdot \frac{s}{t^2}=2\cdot \frac{0.862 m}{0.50^2 s^2}=6.896\ m/s^2$ . The net force that caused this acceleration for a body of mass $m=2.5 kg$ is determined by Newton’s second law $F=m\cdot a=2.5 kg\cdot 6.896 m/s^2=17.24 N$

Answer: The net external force acts on the otter along the incline is $17.24 N$