Asked by Student
Is it impossible to lose all of the kinetic energy in a collision? Or, does a ball which bounces several times before eventually coming to rest show how kinetic energy can completely disappear?
Answers
Answered by
drwls
Yes, it is possible to lose all KE, when two masses of equal and opposite momentum collide and stick together.
A bouncing ball loses a fraction of its kinetic energy with each bounce.
A bouncing ball loses a fraction of its kinetic energy with each bounce.
Answered by
bobpursley
Take a wet glob of bubble gum and slam it into the floor. It sticks with a splat. Momentum is conserved, as the Earth moves. Then the Earth must have some reactionary velocity,
KE remaining= 1/2 Me V^2
But what is that V? Massbubblegum*velocity (let use number, say 10 g, and 2 m/s
KE bubblegum= 1/2 *.01*4= .02J
now conservation of momentum..
.01*2= (Me+.10)V
Vearth= .02/10^24
KE Earth= 1/2 Me (.02/Me)^2=E-4-24
portion of ke remaining= E-28/.02=5E-30
is that close enough to zero (lose all KE)?
KE remaining= 1/2 Me V^2
But what is that V? Massbubblegum*velocity (let use number, say 10 g, and 2 m/s
KE bubblegum= 1/2 *.01*4= .02J
now conservation of momentum..
.01*2= (Me+.10)V
Vearth= .02/10^24
KE Earth= 1/2 Me (.02/Me)^2=E-4-24
portion of ke remaining= E-28/.02=5E-30
is that close enough to zero (lose all KE)?