Question

please help! and sorry for posting here

you are a gymnast of mass 72 kg, initially hanging at rest from a bar. you let go of the bar and fall vertically 92cm to the floor below. upon landing, you bend your knees, bringing yourself to rest over a distance of 35cm. the floor exerts a constant force on your body as you slow down. Determine your speed at impact, and the magnitude of the force the floor exerts on you as you slow down

Answer 1

Use the following equation:
\[v ^{2}=v _{0}^{2}+2ax..........(1)\]
where x is the displacement.
Substituting the given values for the fall gives
\[v ^{2}=0+2\times9.81\times0.92=18.05\]
Therefore the speed at impact v is given by
\[v=\sqrt{18.05}\ ms ^{-1}\]

Answer 2

@kropot72 thankyouu!!! what about the magnitude of the force the floor exerts on the person as it slows down

Answer 3

Using equation (1) again but rearranging to find the acceleration when the final speed is zero we get
\[a=-\frac{v _{0}^{2}}{2x}.............(2)\]
Substituting into (2) to find the decceleration we get

\[a=-\frac{18.05}{2\times 0.35}\]
Using the equation
\[F=ma\]
and sustituting the value found for a and the mass of 72 kg gives
\[F=72\times -\frac{18.05}{2\times 0.35}\ N\]

Answer 4

@kropot72 thankyou soosososos much <3 :))

Answer 5

You're welcome :)