Question

With what force must a man pull on a rope to hold a plank in position if the man weights 60 kg, neglecting the weight of the plank, rope and pulley?

Answer 1

The conditions of equilibrium

F net = 0

Man on the plank as a system

T + N - mg = 0................................1

For plank as a system

3T - N = 0 ....................2

Substituting T from eq 1 in eq 2

we get 3 mg - 3 N - N = 0

3 mg = 4N

3/4 mg = N

now substitute N in eq 1

T = mg - 3/4mg

Mag of Weight = 60

T= 60 - 45

T= 15

Thus force applied is 15 kgf

Answer 2

Answer:

Explanation:

4T=mg

4T=60×10

4T=600

T=600/4

         T=150N