Question

A seesaw has an irregularly distributed mass of 40 kg k g , a length of 3.0 m m , and a fulcrum beneath its midpoint. It is balanced when a 60-kg k g person sits on one end and a 80-kg k g person sits on the other end.

1. Express your answer with the appropriate units. Enter negative value if the center of mass is located closer to the 60-kgkg person and positive value if the center of mass is located closer to the 80-kgkg person.

2. Consider a system consisting of a uniform 3.0-mm long seesaw that has a mass of 40 kgkg and two people of masses 60 kgkgand 80 kgkg sitting on its ends. Find the position of the center of mass of the system relative to the seesaw's midpoint.

Express your answer with the appropriate units. Enter negative value if the center of mass is located closer to the 60-kgkg person and positive value if the center of mass is located closer to the 80-kgkg person.

Answer 1

A)

Taking moment about the end,

(60 x 3) + (2 x 40 d) = 85 x 3

d = (85 x 3 - 60 x 3)/(2 x 40) = 0.938 m

d = - 0.938 m

B)

d = [60 (-3/2) + (40 x 0) + (85 x 3/2)]/(60 + 40 + 85)

d = 0.20 m

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