# Solve the following :

Question:

A body slipping on a rough horizontal plane moves with a deceleration of $4.0 \mathrm{~m} / \mathrm{s}^{2}$. What is the coefficient of kinetic friction between the block and the plane?

Solution:

Vertical equilibrium

$\mathrm{N}=\mathrm{mg}$

For horizontal; ${ }^{\text {Net }}={ }_{\text {ma }}$

$0-f f=m a$

$-\mu N=m a$

$-\mu m g=m a$

$-\mu g=\alpha$

$-\mu g=(-4)$

$\mu=0.4 \mathrm{~m} / \mathrm{s}^{2}$