Question

18.)On as smooth table two blocks of masses 2.5kg and 1.5kg are placed one over the other.If the coefficient of static friction between two blocks is 0.2,the maximum horizontal force to be applied on the lower block so that the two blocks move together is (g=10m/s2)

Answer 1

Frictional force on 1.5 kg mass:

$$\begin{gathered} f=\mu m_{B}g \\ =0.2\times 1.5\times 10 \\ =3N \end{gathered}$$

Acceleration:

$$\begin{gathered} a=\frac{f}{m_B} \\ =\frac{3}{1.5} \\ =2m/s^2 \end{gathered}$$

Maximum force:

$$\begin{gathered} F_{max}=\left(m_A+m_B\right)a \\ =\left(2.5+1.5\right)\left(2\right) \\ =8N \end{gathered}$$