Question

A mass of 8kg rests on a horizontal table . It is connected to a vertically hanging mass of 4kg by a light string passing over a smooth pulley at the edge of the table . The frictional resistance of the table is 2Nkg-¹ for the mass on the table.

What is the acceleration of each mass when the system is free to move ? Take gravity=10ms-² . After one second the string is cut.
a.What is the deceleration of the mass on the table ?
b.How much further will it move before coming rest ? ​

Answer 1

Let the tension be T and acceleration be a. Then,
From FBD of block of mass 8Kg
T=8a ..... eq.1
And, From FBD of block of mass 2Kg
2g−T=2a
⇒T=20−2a=8a from eq.1
⇒a=2m/s
2

⇒T=8a=16N