A pinball with mass 80g is struck by a lever with mass 80g in a pinball machine in an elastic collision. The lever was pulled back 2 cm by a spring with spring constant k=1.4N/cm. What is the speed of the ball just after collision?
M1V1 = M2V2
The Attempt at a Solution
1/2 (2.8)(4)=5.6 5.6=1/2 (80) v^2 <-- trying to find velocity of lever just before contact
5.6/40 = v^2 V=.37
now this is where i get even more stuck, the masses of the ball and the lever are equal and they cancel out in the equation M1V1 = M2V2, which would leave the velocities as being equal. However, the answer choices are as follows:
A) 1.1 m/s
B) 1.4 m/s
C) 11 m/s
D) 14 m/s
If someone can shed some light on how to solve this problem it would be greatly appreciated.