Question

A rope of mass 5 kg is moving vertically with an upward force of 100 N acting at the upper end and a downward force of 70 N acting at the lower end. The tension at the mid point of rope is

• A. 100 N
• B. 85 N
• C. 75 N
• D. 105 N

Answer 1

Answer: (B)

85 N

Applying newtons law of motion, we have
$100-(70+5\times g)=5\times a$
acceleration is given by,$100-70-50=5\times a$
$a=-4m/s^2$ in the downward direction.
Let the tension be T, mass of the half rope will be 2.5 kg,
Substituting this value in the Newton's IInd law of motion gives us
$70+2.5g-T=2.5\times 4$
$T=85$ newton