Four men jumping from a raft

If the velocity is relative to the river, then the velocity of the center of mass of the raft will be 0 m/s, since all four men jumped in with the same velocity and in opposite directions, canceling out the overall momentum. However, if the velocity is relative to the land, then the velocity of the center of mass of the raft will be 2 m/s in the direction of the men's initial jump. In summary, the velocity of the center of mass of the raft is 0 m/s relative to the river and 2 m/s in the direction of the men's initial jump relative to the land.
  • #1
Akash47
53
5
Moved from a technical forum, so homework template missing
Suppose four men are on a square shaped raft.All have jumped mutually perpendicularly into the river from the raft at velocity 2m/s at the same time. What will be the velocity of the center of mass of the raft?
The implied assumption is likely that the mass of the four men is same.
I think the conservation of momentum will work here.But I have drew the scenario and got that if I take two perpendicular sides as positive,then the other two sides will be negative.And also I couldn't relate the direction of the velocity of the four men.Please help me out.
 
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  • #2
Conservation of momentum can be applied along each axis separately. So you only need to think about two men at a time.
 
  • #3
Akash47 said:
What will be the velocity of the center of mass of the raft?

This could be a trick question. Velocity relative to the river or to the land?
 

1. How does the weight of the men affect the raft when they jump?

The weight of the men will affect the raft by causing it to sink lower into the water, potentially making it less stable. This can also depend on the size and buoyancy of the raft.

2. What factors can impact the distance the men can jump from the raft?

Factors such as the force and angle of their jump, the surface tension of the water, and any wind or current can impact the distance the men can jump from the raft.

3. Is it safe for four men to jump from a raft at the same time?

It is generally not recommended for four men to jump from a raft at the same time as it can cause instability and potentially capsize the raft. It is safer for them to jump one at a time.

4. How does the height of the raft affect the jump distance?

The height of the raft can affect the jump distance by increasing or decreasing the potential energy of the jump. A higher raft will give the men more potential energy, allowing them to potentially jump farther.

5. What are the potential risks of jumping from a raft?

The potential risks of jumping from a raft include injury from hitting the water at a high speed or from the impact of the water, drowning if the person is unable to swim or gets stuck under the raft, and potential damage to the raft itself.

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