An electron collides elastically with a stationary hydrogem atom.?

Question

The mass of teh hydrogen atom is 1837 times that of the electron. Assume that all motion, before and after the collision, occurs along the same straight line. What is the ratio of the kinetic energy of the hydrogen atom after the collision to that of the electron before the collision?

Answer 1

ok i fell asleep in physics, but...

1/1837 th of the motion would be transferred to the atom.

and 1836/1837ths would be the speed of the bounced electron.