- #1

- 46

- 8

- Homework Statement
- An astronaut with mass M_a moves across a rectangular space shuttle of length d. If the space shuttle has mass M_s, how far does the shuttle move back?

- Relevant Equations
- Center of mass.

I had solved this question but it didn't seem to be appropriate to post in the classical physics problem as my question is still homework-based.

Originally I had thought this might be a conservation of momentum problem. But since we don't have any initial conditions it leaves too much to guess. A simpler approach would be to track the center of mass of the space shuttle, and it's shift would correspond to the movement of the shuttle backwards.

Admittedly the homework question appears poorly worded but from what I deduced (based on getting the correct) answer, this is occurring in space.

The center of mass of the shuttle itself should be at ##\frac{d}{2}## but I thought this wasn't necessary to use. I figured I could track the center of mass at the origin (where the astronaut starts on the shuttle), and I arrived at:

##\frac{0M_s + dM_a}{M_s + M_d}##

which gave me the correct answer. But after reviewing my thought process I confused myself...since shouldn't I have needed to track the center of mass of the shuttle to track it's movement?

What does this result actually mean in terms of a center of mass shift? I am having trouble understanding it without thinking about the midpoint center of mass of the shuttle.

Originally I had thought this might be a conservation of momentum problem. But since we don't have any initial conditions it leaves too much to guess. A simpler approach would be to track the center of mass of the space shuttle, and it's shift would correspond to the movement of the shuttle backwards.

Admittedly the homework question appears poorly worded but from what I deduced (based on getting the correct) answer, this is occurring in space.

The center of mass of the shuttle itself should be at ##\frac{d}{2}## but I thought this wasn't necessary to use. I figured I could track the center of mass at the origin (where the astronaut starts on the shuttle), and I arrived at:

##\frac{0M_s + dM_a}{M_s + M_d}##

which gave me the correct answer. But after reviewing my thought process I confused myself...since shouldn't I have needed to track the center of mass of the shuttle to track it's movement?

What does this result actually mean in terms of a center of mass shift? I am having trouble understanding it without thinking about the midpoint center of mass of the shuttle.