A high jumper wants to clear the bar at 2.1m. To do so he needs to raise his center of mass to a height of 2.4m. Assuming that air resistance can be neglected and his center of mass is 1.1m above the ground at take-off, determine the required vertical take-off speed.
The jumper has to raise his center of
mass to the height of 2.4, i.e. to move
it by the distance of 2.4 -1.1 =1.3 m
From kinematics
h =Vo•t-g•t^2/2,
0=Vo –gt
Vo=sqrt(2•g•h) =sqrt (2•9.8•1.3) =5.05 m/s