Problem $1.$ Push$-$ups.

Relevant learning goals:

$-$ Analyze torques in a static system.

Subskills: $1,2$

A common exercise to strengthen chest, arm, and shoulder muscles is the push$-$up$.$

$($a$)$ Draw a diagram showing all forces acting on the body.

$($b$)$ What percentage of your body weight do you need to apply as a force with your hands? Assume $-$ very roughly $-$ that a person's center of mass is $\backslash (55\backslash \%\backslash )$ of their height off the ground when standing and that a person's shoulder's are $\backslash (80\backslash \%\backslash )$ of their height.