posted by BBell
You build a toy model of a water slide. A red 225 g toy car slides down a 40 degree frictionless ramp. At the bottom, just at it exists onto a horizontal part of the slide, it collides with a purple 450 g car at rest. How high should you make the water slide so that the red toy car gives the purple car a speed of 200 cm/s? Assume the collision is perfectly elastic.
(1/2) m u^2 = m g h
so u = sqrt (2 g h) (remember that, use it all the time)
to get u
.225 u = .225 u' + .450 kg * 2 m/s
(1/2)(.225 ) u^2 = (1/2)(.225) u'^2+ (1/2)(.450)(4)
once you have u, you can find gh