Physics Hwk. problem: Conservation of Linear Momentum

AI Thread Summary
A 55 kg swimmer runs off a stationary 225 kg raft at +4.4 m/s, prompting a discussion about calculating the raft's recoil velocity using conservation of linear momentum. The initial poster used the equation vf2 = -m1*vf1/m2 but received an incorrect answer. Another participant confirmed the equation is correct and shared their own similar problem, which they solved correctly. The final answer discussed was -1.08 m/s, with a note that significant digits may affect the result if using a specific platform like Webassign. The conversation emphasizes the importance of proper rounding in physics calculations.
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55 kg swimmer is standing on a stationary 225 kg floating raft. The swimmer then runs off the raft horizontally with a velocity of +4.4 m/s relative to the shore. Find the recoil velocity that the raft would have if there were no friction and resistance due to the water.

I used the equation vf2=-m1*vf1 divided by m2, but the answer is wrong. Did I use the wrong equation? Please Help!
 
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Hey I had this same homework problem. Almost exactly infact. The only thing different is your raft weighs 225kg and mine weighed 230kg. And I got the problem correct so I think I can help you.

The equation you are using is correct. What was your answer?
 
Physics Hwk. Problem: Conservation of Linear Momentum

Thanks, the answer i got is -1.08.
 
That should be the correct answer then. Unless your using webassign and it requires 3 significant digits. Then you are rounding too soon.
 

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