Question

A block of mass $20 kg$ is sliding on a surface is incline at an angle of $45^{\circ}$ with the horizontal. What will be th acceleration of the block if the coefficient of kineti friction between the block and the surface is $0.7 ?$

• A. $2.01 m / s ^{2}$
• B. $2.08 m / s ^{2}$
• C. $3.08 m / s ^{2}$
• D. None of these

Answer 1

Answer: (B)

Acceleration down the inclined plane
$a=g\left(\sin \theta-\mu_{k} \cos \theta\right)$

$a=9.8\left(\frac{1}{\sqrt{2}}-\frac{0.71}{\sqrt{2}}\right)$
$a=\frac{9.8}{\sqrt{2}}(1-0.7)$
$ \Rightarrow a=2.08$