Question

A man pulls a box across a rough surface at a constant speed. If the applied force is 100-N, how much is the frictional force?

Option 1: 100 N
Option 2: 50 N
Option 3: 0 N
Option 4: 200 N

Answer 1

The frictional force is 100-N if a box is pulled with 100-N force across a rough surface at constant speed, due to the balance of forces required for constant velocity.

Step-by-step explanation:

If a man pulls a box across a rough surface at constant speed and the applied force is 100-N, then the frictional force must also be 100-N. This is because, according to Newton's first law of motion, an object moving at constant velocity must have no net external force acting on it. Since the box is moving at a constant speed, the forces must be balanced, meaning the applied force and the frictional force are equal in magnitude but opposite in direction.