With kinetic energy and momentum conservation, you have two equations in two unknowns, m1 and v2'
The ' symbol denotes final conditions.
m1 v1 + m2v2 = m1v1' + m2v2'
(m1/2)v1^2 + (m2/2)v2^2 = (m1/2)v1'^2 + (m2/2)v2'^2
Substitute in m2 = 1.1,
v1 = 1.2, v1' = -2.3 and v2 = 4.2
Now do the math.
It will help to prove, or know, that
v1 - v2 = v2' - v1'
(The relative velcity of the two balls changes sign but keeps the same absolute value)
The only unknown is v1 in that equation.
1.2 -4.2 = v2' + 2.3
v2 = -5.3
Now solving for m1 is easy.
You don't say what the units of velocity are. Just make sure they are the same for all.
two balls collide in a head on elastic collision and rebound in opposite directions. One ball has velocity 1.2 before the collision and -2.3 after. the other ball has a mass of 1.1 kg and a velocity of -4.2 before the collision. What is the mass of the first ball? What is the velocity of the second ball after the collision?
please show work
1 answer