# A 48.4 kg crate rests on a level floor at a shipping dock. The coefficients of static and kinetic...

## Question:

A {eq}48.4 \ kg {/eq} crate rests on a level floor at a shipping dock. The coefficients of static and kinetic friction are {eq}0.578 {/eq} and {eq}0.428 {/eq}, respectively.

(A) What horizontal pushing force s required to

(a) Just start the crate moving and

(b) Slide the crate across the dock at a constant speed?

## Friction force:

When two rough surfaces come in contact with each other then a force of friction develops between them.

This force of friction is equal to the product of coefficient of friction {eq}\mu {/eq} and reaction between the surfaces.

{eq}F = \mu\ R {/eq}

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{eq}*m = 48.4\ kg\\ *\mu_s = 0.578\\ *\mu_k = 0.428\\ {/eq}

## Part(a)

force required to just start the crate moving is equal to ststic frictional...

The Five Laws of Friction

from

Chapter 2 / Lesson 10
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Friction is a force that slows things down and keeps them from moving. In this lesson, learn about five simple rules that will help you to understand and calculate friction forces.