Question

A box is sliding along a frictionless surface and gets to a ramp. Disregarding friction, how fast should the box be going on the ground in order to slide up the ramp to a height of 2.5 meters, where it stops? (Use g = 9.8 m/s2.)

2.2 m/s
7.0 m/s
9.9 m/s
24 m/s

Answer 1

Use conservation of energy: 1/2 m v^2 = m g h → v = sqrt(2 g h). With g = 9.8 m/s^2 and h = 2.5 m,

v = sqrt(2·9.8·2.5) = sqrt(49) = 7.0 m/s.