Biophysics Problem 12

A high jumper jumps \(1.2\; m\)  straight up. With what speed did he leave the ground?

This is a straightforward problem in kinematics.

You should be able to make a list of three known variables and one unknown.

Make this list. Be careful with the sign of each quantity.

You should have the following:

known variables:    
\(s = 1.2\; m \\ v = 0 \\ a = -9.8\; m/s^2\)

unknown variables:  
\(u = ?\)

Now use the proper equation to solve for \(u.\)

The equation that you should use is:

\(v^2 = u^2 + 2\;a\;s\)

\(v^2 = u^2 + 2\;a\;s\\ u = \sqrt{v^2 - 2\;a\;s}\\ = \sqrt{0^2 - 2(-9.8)(1.2)}\\ = 4.9\frac{m}{s}\)