In the high jump, Frank's kinetic energy is transformed into gravitational potential energy without the aid of a pole. With what minimum speed must Fran leave the ground in order to lift her center of mass 1.89m and cross the bar with a speed of 1.16m/s?

Answer:
1.27 m/s
Incorrect
The correct answer is: 6.20 m/s

someone please explain what i did....

1 answer

when she crosses the bar she is moving in horizontal direction
Ux = 1.16 the whole time.

Now the vertical problem:
(1/2) m Vi^2 = m g h
so
Vi = sqrt (2gh) {This is worth remembering}
Vi = sqrt (2*9.81*1.89) = 6.09
so
|v| = sqrt (1.16^2+6.09^2) = 6.20 sure enough