Question

A block of mass 8kg is pulled along a horizontal frictionless surface by a rope of mass 2 kg. A force of 100N is applied at the free end of the rope.Find the force exerted by the rope on the block.

Answer 1

here both the rope and the block move with teh same acceleration, say 'a'.

Now, for the combined system

F = Ma

here

F = 100 N

M = 8 kg + 2 kg = 10 kg

so,

a = 100 / (8+2)

or

a = 10 m/s²

now, the force exerted on the block will be

f = ma

here

m = 8 kg and a = 10 m/s²

so,

f = 8 x 10

thus, force

f = 80 N