Question

A person moving into a new apartment is dragging a large trunk (mass of 35 kg) down the hallway at a constant velocity, with a force of 72 N [right]. Find the coefficient of kinetic friction for the trunk and the floor.

Answer 1

To find the coefficient of kinetic friction between the trunk and the floor, we first need to calculate the frictional force acting on the trunk.

The force of friction can be calculated using the formula:

Frictional force = coefficient of kinetic friction × normal force

In this case, the normal force is equal in magnitude but opposite in direction to the force applied to the trunk, which is 72 N to the right. So the normal force is 72 N [left] = -72 N [right].

Since the trunk is moving at a constant velocity, the net force on the trunk is zero. Therefore, the frictional force (opposite to the direction of motion) must be equal in magnitude and opposite in direction to the force applied to the trunk (72 N [right]).

Frictional force = 72 N [right]

Now we can calculate the coefficient of kinetic friction:

Frictional force = coefficient of kinetic friction × normal force

72 N = coefficient of kinetic friction × 72 N

coefficient of kinetic friction = 72 N / 72 N

coefficient of kinetic friction = 1

Therefore, the coefficient of kinetic friction between the trunk and the floor is 1.