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 9.47 m work plank which weighs 115 N and is secured with a hinge on the opposite end. Worker B will stand on the plank 4.88 m from worker A. Worker B also brings up his paint can, mc = 3.50 kg, which he places 0.430 m from where he is standing on the plank (between the two workers). Worker A unfortunately needs to supply 509 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 = 509N*9.47m - 115N*8.98m/2 - B*(9.47-4.88)m
- 3.5kg*9.81m/s²*(9.47-4.88+0.43)m
B * 4.59m = 4084 N·m
B = 889.76 N

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

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