How long must a 25 degree ramp be to slow to a momentary stop a runaway truck moving along a truly horizontal highway at 85 miles per hour

Answer 1

Ignoring friciton, the KE is has must be converted to GPE

1/2 m v^2=mgh
solve for h (convert mph to m/s first)

then, length of ramp at 25 degrees..

sin25=H/L or
length= height h above / sin25