I'm having a little trouble figuring this one out..

two blocks are free to slide along a frictionless wooden track ABC (basically a ramp with A 5m up and B at the base of the ramp and C a distance off to the right. A block of mass m1=5kg is dropped from A (5m up). Protruding from its front end is the north pole of a strong magnet, repelling the north pole of an identical magnet embedded in the back end of the block of mass m2=10kg (at point B at the base of the ramp), initially at rest. The two blocks never touch. Calculate the maximum height to which m1 rises after the elastic collision.
A|
--\
---\____________C
----B
just round the slope off, and thats all the details given in the picture.

What i have so far is that Pi=Pf and Ki=Kf because it is elastic, so

we have Pi= m1Vi1 and Pf=m1vf,1 + m2v2
and Ki=1/2 m1vi^2 and Kf=1/2m1vf,1^2 + 1/2 m2v2^2

This would be much clearer if I knew how to do subscripts on here.. but am I on the right track? I guess what I'm missing is how to find the initial velocity, which is probably from another lesson (I've fallen behind a little bit and I'm still trying to catch up)

thanks for any help!

 

How far would block M1 rise? Does this mean rebound back towards A after colliding with M2? If so, I'm thinking trick question. M1 transferrs all it's energy to M2 and m1 stops at B while M2 moves to C. Answer = 0.

 

Yes, it means back towards A. Even with the elastic collision would it stop?

 

M1 will have some kinetic energy (Ki) from falling plus the two opposite force of the magnetic flux. Determine the Magnetic flux as a form of energy. Determine those properties as a scalar and vector forms of the magnetic energy density flux. What equations are you using, such asFaraday's law or Neuton's law in your physic class?

 

Newtons, we are just learning about momentum though.. I don't think the fact that its a magnet makes any difference in this particular problem, just that its perfectly elastic, right?

 

Proof that you can find ANYTHING on FTE!!!

 

Haha, yes cmpd.. there's always someone here to help me with my homework when I can't figure it out, its great!

 

M1 will starts at velocity 0 m/s at V1 with KE=0 and will need to determine velocity V2 at 5m at point B for M1. M2 (10 kg) initial velocity, V3 is 0. Momentum is equal to mass times velocity. V2 = V1 + at , a = 9.8 (m/s)/s (gravity). Time it take 5kg mass to fall 5 meters, t = 1.02 seconds.

Begining physics sometimes used a= 10 (m/s)/s. Check your physic book for what constant to use for gravitional acceleration.

The final velocity of M1 (5kg), V2 = 10 m/s = Vf

 

So, what was the correct answer?

 

You know, girls are a lot more interesting...............probably why I barely survived physics class - skip the theory and go right after practical application.

 

Yeah, thats why I don't know whats going on, haha.

I'll post the right answer later tonight.

 

The final velocity of M1 (5kg), V2 = 10 m/s = Vf just before impact of M2.

 

1975ford's got it, and to find momentum, just take the mass (5kg) and multiply it times the 10 m/s so you get 50 Newtons of force.

Pi=50N=Pf(from what you said was given)
Ki=250 N/s=Kf(from what was given)

 

What was the answer.

 

oops, forgot about this thread! here's the answers..

speed of m1 just before collision = 9.90m/s
speed of m1 just after collision = -3.30m/s
at it rose to .556 m