Question

You are trying to hold your 550 g physics books with your hand against a vertical wall. Using a force sensor you know that the force you are applying is 10.0 N. Below the book on the floor you have placed a motion sensor. The position time graph for the book is given. Find the coefficient of kinetic friction.

Answer 1

Answer:

Above answer

Explanation:

The book's position is changing linearly with time, so its velocity is constant. This means that the net force acting on the book in the direction parallel to the surface is

∑ F = 10.0 N - n = 0

where n is the magnitude of the normal force on the book due to the wall, and the net force perpedicular to the surface is

∑ F = f - (0.550 kg) g = 0

where f is the mag. of kinetic friction, and f = µn where µ is the coefficient of kinetic friction.

Then

• n = 10.0 N

• f = (0.550 kg) g = 5.39 N

• 5.39 N = µ (10.0 N)

==>   µ = 0.539

Answer 2

The book's position is changing linearly with time, so its velocity is constant. This means that the net force acting on the book in the direction parallel to the surface is

∑ F = 10.0 N - n = 0

where n is the magnitude of the normal force on the book due to the wall, and the net force perpedicular to the surface is

∑ F = f - (0.550 kg) g = 0

where f is the mag. of kinetic friction, and f = µn where µ is the coefficient of kinetic friction.

Then

• n = 10.0 N

• f = (0.550 kg) g = 5.39 N

• 5.39 N = µ (10.0 N)

==>   µ = 0.539