Question

A 5.00 x 102 kg hot air balloon takes off from rest at the surface of the earth. The buoyant force lifts the balloon straight up, performing 9.70 x 104 J of work on the balloon. At the instant the balloon's upward speed is 4.08 m/s, the balloon will be ____ m above the surface of the earth.

Answer 1

KE+PE=Total Work
((1/2)mv^2) + (mgh) = W
W = 9.7x10^4 J
v = 4.08 m/s
m = 500 kg
g = 9.8 m/s^2
Rearrage for h
h = (W - ((1/2)mv^2)) / mg
h = 18.9466m

Answer 2

Excellent