Applied Mechanics - Engineering

Q1:

A body A of mass 6.6 kg which is lying on a horizontal platform 4.5 m from its edge is connected to the end of a light string whose other end is supporting a body of mass 3.2 kg as shown in below figure. If the friction between the platform and the body A is 1/3, the acceleration is

A 0.5 m/sec2

B 0.75 m/sec2

C 1.00 m/sec2

D 1.25 m/sec2.

ANS:C - 1.00 m/sec2

We need to use D'Alembert's principle for 2blocks.
Assumimg a as acceleration for hanging block we can write Eqn 1 as 3.2g-T=3.2a.
And Eqn 2 as T-(1/3. 6.6g) = 6.6a.
Solving both we get a = 1m/s2.