Question

A painter stands a horizontal platform which has a mass of 20kg and is 5m long, the platform is suspended by two vertical ropes , one attached to each end of the platform . the mass of the painter is 70kg . if he is standing 2m from the centre of the platform . Calculate the tension in each of the ropes.​

Answer 1

Answer:

R = 715.4 N

L =  166.6 N

Explanation:

ASSUME the painter is standing right of center

Let L be the left rope tension

Let R be the right rope tension

Sum moments about the left end to zero. Assume CCW moment is positive

R[5] - 20(9.8)[5/2] - 70(9.8)[5/2 + 2] = 0

R = 715.4 N

Sum moments about the right end to zero

20(9.8)[5/2] + 70(9.8)[5/2 - 2] - L[5] = 0

L =  166.6 N

We can verify by summing vertical forces

116.6 + 715.4 - (70 + 20)(9.8) ?=? 0

                                             0 = 0  checks

If the assumption about which side of center the paint stood is incorrect, the only difference would be the values of L and R would be swapped.