two cars of equal mass with equal speeds traveling perpendicular to one another collide completely in elastically. what percentage of the cars' total energy is lost in the collision?

Answer 1

ritzi as in spikey sea urchins?

If a collision is elastic, no kinetic energy is lost. That is what an elastic collision means.

Answer 2

two cars of equal mass with equal speeds traveling perpendicular to one another collide completely inelastically. what percentage of the cars' total energy is lost in the collision?

Answer 3

If they stick together then momentum is conserved

x momentum before = m v
y momentum before = m v

x momentum after = 2 m U cos theta
y momentum after = 2 m U sin theta
so
2 U cos theta = v
2 U sin theta = v
or
cos theta = sin theta so theta = 45 degrees
cos theta = cos 45 = sqrt2/2 = sin theta

2 U = v/cos theta = 2 v /sqrt 2
so
U = v/sqrt 2

Ke before = 2 (1/2) m v^2 = m v^2
Ke after = (1/2) (2m) U^2 = m v^2/2
so half the Ke would be lost if there were no bounce at all