Question

Block A is placed on block B whose mass is greater than that of A. There is friction between blocks while the ground is smooth. A horizontal force P increasing linearly with time begins to act on A. The accelerations a₁ and a₂ of A and B respectively are plotted in a graph against time. Which of the following graphs represents the real situation?

Answer 1

Correct option is (C) 

Now for f = mm1 g; this is the maximum frictional force;

∴ f = m₂ a₂

µm₁ g = m₂ a₂

⇒ a₂ = \(\frac{\mu m_1 g}{m_2}\) which is constant

And P – f = m₁a

⇒ P – µ mg = m₁a

a₁ = \(\frac{kt - \mu m_1 g}{m_1}\)

Answer 2

Correct answer is