Center of mass question (man on a boat)

AI Thread Summary
The discussion revolves around a physics problem involving a man walking on a boat and the resulting change in the center of mass (CM). The initial calculations suggest that the CM relative to the boat shifts when the man moves, but the absolute position of the CM remains unchanged due to the conservation of momentum. Participants express confusion about the lack of a defined origin for measuring absolute positions, which complicates the interpretation of the problem. The calculations indicate that the CM moves left as the man walks right, but there is uncertainty about the correctness of the results provided by SmartPhysics. Overall, the problem highlights the complexities of center of mass calculations in a frictionless system.
ddtozone
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Homework Statement



A man with mass m1 = 60 kg stands at the left end of a uniform boat with mass m2 = 169 kg and a length L = 2.7 m. Positive x is pointing to the right. Assume there is no friction or drag between the boat and water. After the man walks to the right edge of the boat, what is the new location the center of the boat?
(The boat lies on the x-axis, so they're looking for the absolute position of the center.

Homework Equations



X=(m1x1+m2x2)/(m1+m2)
The absolute location of the CM will not change.

The Attempt at a Solution


First the CM equation (169*1.35)/(169+60) gives me x = 1 (relative to the boat) as the position of the center of mass, which I use as a reference point for the x-axis.
When the man moves to the right, I plug in (60*2.7+169*1.35)/(169+60) and I get x = 1.7 relative to the boat. Since the center has moved to the left, I do 1.7 - 1 = 0.7 to find the distance the center has gone. Finally I subtract that change in distance from the original position with 1.35 - 0.7 = 0.65. But SmartPhysics says this is wrong. Does someone have any further insight here? Thank you!
 
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ddtozone said:
A man with mass m1 = 60 kg stands at the left end of a uniform boat with mass m2 = 169 kg and a length L = 2.7 m. Positive x is pointing to the right. Assume there is no friction or drag between the boat and water. After the man walks to the right edge of the boat, what is the new location the center of the boat?
(The boat lies on the x-axis, so they're looking for the absolute position of the center.

The question doesn't provide an origin against which positions are to be measured, so how is 'absolute position' to be interpreted? Is this the precise and complete wording of the problem?
 
gneill said:
The question doesn't provide an origin against which positions are to be measured, so how is 'absolute position' to be interpreted? Is this the precise and complete wording of the problem?

because this is a question with multiple parts, and the answers to the first parts are based on the reference points of the boat's initial position, with the left of the boat starting at x=0. I guess there's a chance that SmartPhysics has an error, but I'm completely stumped.
 
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