Question

2. A 200.0-kg bear grasping a vertical tree slides down at constant velocity. What is the friction force between the tree and the bear?

Answer 1

Answer: 1960 N

Step-by-step explanation:

The bear is sliding down at constant velocity: this means that its acceleration is zero, so the net force is also zero, according to Newton's second law:

`F_(net)=ma=0`

There are two forces acting on the bear: its weight W, pulling downward, and the frictional force Ff, pulling upward. Therefore, the net force is given by the difference between the two forces:

`F_(net)=W-F_f=0`

From the previous equation, we find that the frictional force is equal to the weight of the bear:

`F_f=W=mg=(200.0 kg)(9.8 m/s^2)=1960 N`