Question

A 52 kg pole vaulter running at 11 m/s vaults over the bar. Her speed when she is above the bar is 1.2 m/s. The acceleration of gravity is 9.8 m/s 2 . Find her altitude as she crosses the bar. Neglect air resistance, as well as any energy absorbed by the pole. Answer in units of m.

Answer 1

6.1 m

Step-by-step explanation:

m = Mass of person = 52 kg

h = Altitude

v = Velocity

Kinetic energy of the person on the ground

`(1)/(2)mv^2=(1)/(2)52* 11^2\\ =3146\ J`

Kinetic energy of the person at the top

`(1)/(2)52* 1.2^2\\ =37.44\ J`

At the top the potential energy is given by

`mgh=52* 9.8h`

Balancing the energy of the system

`3146=37.44+52* 9.8h\\\Rightarrow h=(3146-37.44)/(52* 9.8)\\\Rightarrow h=6.1\ m`

Her altitude is 6.1 m