A young work crew is trying to quickly finish some touch-up painting to complete

Question

A young work crew is trying to quickly finish some touch-up painting to complete a job. Rather than setting up a secure work area, they decide to try a shortcut. Worker A will hold the far end of a 8.49 m work plank which weighs 1.10 × 102 N and is secured with a hinge on the opposite end. Worker B will stand on the plank 4.77 m from worker A. Worker B also brings up his paint can, mc = 3.56 kg, which he places 0.250 m from where he is standing on the plank (between the two workers). Worker A unfortunately needs to supply 4.70 × 102 N of force to hold the end of the plank. How much does worker B weigh? The acceleration due to gravity is g = 9.81 m/s2.

Explanation / Answer

Sum the moments about the hinge:
M = 0 = 470N*8.49m - 110N*8.49m/2 - B*(8.49-4.77)m
- 3.56kg*9.81m/s²*(8.49-4.77+0.250)m
B * 3.72m = 2917.75 N·m
B = 784.34 N

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.