A 21.0-kg block is initially at rest on a horizontal surface. A horizontal force of 79.0 N is required to set the block in motion, after which a horizontal force of 65.0 N is required to keep the block moving with constant speed.a) Find the coefficient of static friction between the block and the surface.b) Find the coefficient of kinetic friction between the block and the surface.

Question
Asked Oct 9, 2019

A 21.0-kg block is initially at rest on a horizontal surface. A horizontal force of 79.0 N is required to set the block in motion, after which a horizontal force of 65.0 N is required to keep the block moving with constant speed.

a) Find the coefficient of static friction between the block and the surface.

b) Find the coefficient of kinetic friction between the block and the surface.

check_circleExpert Solution
Step 1

Write the expression for static frictional force that sets the block in motion

F ,mg
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F ,mg

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Step 2

Substituting the values

(79.0 N) 4, (21.0 kg)(9.8 m/s2)
4=0.384
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(79.0 N) 4, (21.0 kg)(9.8 m/s2) 4=0.384

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Step 3

Write the expression for the kinetic frictional force...

ng
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ng

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