a
(a)

Given: acceleration of block \(A\) varies with time as shown in figure To find the value of coefficient of kinetic friction between the block \(A\) and \(B\) Solution:

Force is applied on block \(B\). The moment when the block \(A\) starts sliding is the moment when the applied force \(F\) is greater than the frictional force between the two blocks.

Apply Newton's Second law of motion we get

\(\operatorname{ma}_i=\mu g m\)

\(\Rightarrow a _{\Lambda}=\mu g\)

\(\Rightarrow 4.9=\mu(9.8)\)

\(\Rightarrow \mu=0.5\)

is the value of coefficient of kinetic friction between the block \(A\) and \(B\)