Blocks (mass 2.00kg ) and (mass 11.50kg ) move on a frictionless, horizontal sur
ID: 2148647 • Letter: B
Question
Blocks (mass 2.00kg ) and (mass 11.50kg ) move on a frictionless, horizontal surface. Initially, block is at rest and block is moving toward it at 10.0m/s . The blocks are equipped with ideal spring bumpers. The collision is head-on, so all motion before and after the collision is along a straight line. Let be the direction of the initial motion of .a)Find the maximum energy stored in the spring bumpers and the velocity of each block at that time.
Find the maximum energy.
b)Find the velocity of A.
c)Find the velocity of B.
d)Find the velocity of each block after they have moved apart.
Find the velocity of A.
Explanation / Answer
Let's answer the final-velocity question first:
Total momentum = (2.00 kg)(10.00 m/s) = 20kg-m/s
After collision (elastic):
KE = 0.5 mv^2 = 1.0(100) =100 J
100 J = 1v1^2 +5.5v2^2
m1v1 + m2v2 = 20 kg-m/s
v1 = 20/m1 - m2v2/m1
v1 =10- 5.5v2
100 J = 1v1^2 + 5.5v2^2
100J = 1(100- 110v2 +30.25v2^2)+ 5.5v2^2
v2=2.8m/s
If we simply assume that the KE is all stored in the spring, during the collision, then the stored energy = 100 J.
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