- #1
Puddles
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Homework Statement
A ball of mass m1 is aligned above a ball of mass M2 (with slight separation), and the two are dropped simultaneously from height h. (Assume the radius of each ball is negligible compared to h.) (a) If M2 rebounds elastically from the floor and then m1 rebounds from M2, what ratio m1/M2 results in M2 stopping upon its collision with m1? (b) What height h does m1 reach?
Homework Equations
KE = .5mv^2
P = mv
The Attempt at a Solution
Okay, so I drew a diagram and used cons. of momentum and energy to find VM for both and set them equal to each other, but there's something wrong in my math because I know my ratio should be 3:1 and I'm not getting that. Here's what I did as best as I can type out on a computer:
Cons. Momentum)
Pi=Pf
(m1-M2) sqrt(ugh)=m1v+M2V, with (m1-M2) because M2 has a negative momentum after it strikes the ground
((m1-M2) sqrt(2gh) - m1v)/M2 = V
Cons. Energy)
1/2(m1+M2)(sqrt(2gh))^2 = 1/2(m1v^2) + 1/2(M2V^2)
sqrt( (2gh(m1+M2)-mv^2)/M2) = V
I think it's a math issue since when I'm setting them equal to each other my work is only getting more complex…
I don't know what I'm doing wrong because I thought my equations were okay, so if someone could explain how you get through this I would be very thankful.