In: Physics
Consider a problem involving tow rubber balls. The upper ball has half the mass of the lower ball. Both are dropped from the same height and so they arrive at thetable traveling downward at a given speed v0. Assume the lower ball bounces perfectly elastically off the table, and is now moving upward at v0, then bounces perfectlyelastically off the upper ball (which at that moment still moving downward at v0.) Find the final speed upward of the upper ball immediately after the collisions. (Hint will begreater then v0).
Side note: I tried this and got 3*v0. This is not the right answer.
The collision between the upper and the lower ball is perfectly elastically, so we know that the total kinetic energy and the total linear momentum of the system is conserved.
The upper ball has half the mass of the lower ball so,
Now, apply conservation of total linear momentum of the system,
inserting eq. (1) into (2), we obtain