A ball with a mass of # 6 kg# is rolling at #16 m/s# and elastically collides with a resting ball with a mass of # 1 kg#. What are the post-collision velocities of the balls?
These momentum problems are the first in physics where you're responsible for managing a (relatively) large number of variables.
Which is derived starting from,
Then, by factoring out (2), and dividing the expansion by (1).
From here, since ball B is at rest, it's easy. Consider,
Now, consider the conformity with the law of conservation of momentum, and substituting this variable in,
and by extension,
From this calculation, we can understand that:
In perfectly elastic collisions, all of the energy or momentum is transferred perfectly from one body to the other, if one is at rest.