Mass is a measure of the amount of matter in an object.  In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.

The mechanical advantage of a wheel and axle is the input radius divided by the output radius:

MA = \( \frac{r_i}{r_o} \)

In this case, the input radius (where the effort force is being applied) is 6 and the output radius (where the resistance is being applied) is 5 for a mechanical advantage of \( \frac{6}{5} \) = 1.2

MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{75 lbs.}{1.2} \) = 62.5 lbs.

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

Solving for d_b, our missing value, and plugging in our variables yields:

d_b = \( \frac{R_ad_a}{R_b} \) = \( \frac{55 lbs. \times 9 ft.}{20 lbs.} \) = \( \frac{495 ft⋅lb}{20 lbs.} \) = 24.75 ft.

Potential energy is the energy of an object by virtue of its position relative to other objects. It is energy that has the potential to be converted into kinetic energy.

Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.