Question

Ignoring details associated with friction, extra forces exerted by arm and leg muscles, and other factors, we can consider a pole vault as the conversion of an athlete’s running kinetic energy to gravitational potential energy. If an athlete is to lift their body 4.8 m during a vault, what speed must they have when they plant the pole?

a) 6.7 m/s
b) 8.5 m/s
c) 10.2 m/s
d) 12.0 m/s

Answer 1

To lift their body 4.8 m during a vault, the athlete must have a speed of approximately 9.72 m/s when planting the pole.

Step-by-step explanation:

To determine the speed an athlete must have when planting the pole in order to lift their body 4.8 m during a vault, we can use the principle of conservation of energy. The athlete's initial kinetic energy from running will be converted into gravitational potential energy when they reach the peak of their vault. We can equate the initial kinetic energy to the potential energy:

1/2mv02 = mgh

Simplifying, we find:

v02 = 2gh

Plugging in the given values of h = 4.8 m and g = 9.8 m/s2, we find:

v02 = 2 * 9.8 * 4.8

v02 = 94.464

Taking the square root of both sides, we find:

v0 = √(94.464)

v0 = 9.72 m/s

Therefore, the athlete must have a speed of approximately 9.72 m/s when planting the pole.