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# Physics - Coefficients of Static and Kinetic Friction

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A 23.0 kg block is initially at rest on a horizontal surface. A horizontal force of 70.0 N is required to set the block in motion. After it is in motion, a horizontal force of 56.0 N is required to keep the block moving with constant speed. Find the coefficients of static and kinetic friction from this information.
Âµs =
Âµk =

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https://brainmass.com/physics/newtons-laws/physics-coefficients-static-kinetic-friction-204947

## SOLUTION This solution is FREE courtesy of BrainMass!

(1) The force F of static friction is the force required to set the block in motion, namely, 70 N.

F = (mu) * mass * g

70 = (mu) * 23 * 9.8

mu = 70 / (23 * 9.8) = 0.31

The coefficient of static friction, mu(static), is 0.31.

(2) The force F of kinetic friction is the force required to keep the block moving at constant speed, namely, 56 N.

F = (mu) * mass * g

56 = (mu) * 23 * 9.8

mu = 56 / (23 * 9.8)

mu = 0.248

The coefficient of kinetic friction, mu(kinetic), is 0.248.

This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!