A student uses a force P of magnitude 86 N to push a 7.0 kg block across the ceiling of his room…..?

If the coefficient of kinetic friction between the block and the ceiling’s surface is 0.40, what is the magnitude of the block’s acceleration?

Answer 1

The Frictional force Ff is:

Ff=µN
=µ(Fsinθ-mg)

The force parallel to the ceiling Fc is:

Fc=Fcosθ-Ff

this can also be represented as:

Fc=ma

Putting this all together:

a=Fc/m

=(Fcosθ-Ff)/m

=(Fcosθ-µ(Fsinθ-mg))/m

=(86*cos(70)-0.40*
(86*sin(70)-7.0*9.8))/7.0

=3.5 m/s²

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