A 40 N crate starting at rest slides down a frictionless 6 meter high the hori A

Question

A 40 N crate starting at rest slides down a frictionless 6 meter high the hori ANS: 10.8 m/s 3) (not long) ramp inclined at 30° to zontal. What is the speed of the crate at the bottom of the incline? 4) An athlete jumping vertically on a trampoline leaves the surface with a velocity of 8.5 m/s upward. What maximum height does she reach? ANS: 3.7 m Find the height from which you would have to drop a ball so that it would have a speed of 9 m/s just before it reaches the ground? ANS: 4.1 m S) A 50 kg pole vaulter running at 10 m/s vaults over the bar. Her speed when she is above the bar is 1 m/s. Neglecting air resistance and any energy absorbed by the pole, determine her altitude as she crosses the bar. ANS: 5 m 6) A child and a sled with a combined mass of 50 kg slide down a frictionless slope. If the sled starts from rest and has a speed of 13 m/s at the bottom, what is the height of the hill? ANS: 8.6 m 7) 8) A bead of mass m 5 kg is released from point A and slides on the frictionless track shown below. Determine (a) the bead's speed at point B and (b) the bead's speed at point C ANS: (a) 5.9 m/s; (b) 7.7 m/s 3.20 m 2.00 m

Explanation / Answer

3)
Conserving the enerigies :
mgh = 1/2mv^2
gh = 1/2v^2
v = (2gh)^(1/2)
v = (2*9.8*6)^(1/2)
v = 10.84 m/s

4)
Conserving the enerigies :
mgh = 1/2mv^2
gh = 1/2v^2
h = (1/2g)v^2
h = (1/(2*9.8))*8.5^2
h = 3.686 m

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