At the peak of its vertical flight, a fireworks shell explodes into two pieces.
ID: 1408023 • Letter: A
Question
At the peak of its vertical flight, a fireworks shell explodes into two pieces. Piece 1 has four times the speed of piece 2
a) What is the ratio of the inertias of the pieces?
b) What is the ratio of their kinetic energies?
Two carts are initially moving to the right on a low-friction track, with cart 1 behind cart 2. Cart 1 has a speed twice that of cart 2 and so moves up and rear-ends cart 2, which has twice the inertia of cart 1.
a) Suppose that the the initial speed of cart 2 is v. What is the speed of cart 1 right after the collision if the collision is elastic?
b) What is the speed of cart 2 right after the collision if the collision is elastic?
Explanation / Answer
(1)
(a)m1v1+m2(-v2)=0
v2 is negative because the pieces will move in opposite directions
m1(4V2)=m2V2
m1/m2=1/4
(b)KE1/KE2= [(1/2m1V12)/(1/2m2V22)
KE1/KE2=(m1/m2)*(V1/V2)2
KE1/KE2=(1/4)(4/1)2
KE1/KE2=4
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