A 52-kg pole vaulter running at 12 m/s vaults over the bar. Her speed when she is above the bar is 0.7 m/s. Neglect air resistance, as well as any energy absorbed by the pole, and determine her altitude as she crosses the bar.

Answer 1

hmax = (V^2-Vo^2)/2g.
hmax = 0-144/-19.6 = 7.35 m.

V = Vo + gt.
t = (V-Vo)/g = (0.7-0)/9.8 = 0.0714 s.

h = ho - 0.5g*t^2'
h = 7.35 - 4.9*(0.0714)^2 = 7.325 m. =
her Alt.

Answer 2

If an automobile engine delivers 48.2 hp of power, how much time will it take for the engine to do 6.80 ✕ 105 J of work? (Hint: Note that one horsepower, 1 hp, is equal to 746 watts.)