Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.

To balance this lever the torques on each side of the fulcrum 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_a, our missing value, and plugging in our variables yields:

d_a = \( \frac{R_bd_b}{R_a} \) = \( \frac{60 lbs. \times 3 ft.}{25 lbs.} \) = \( \frac{180 ft⋅lb}{25 lbs.} \) = 7.2 ft.

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

To balance this lever the torques on each side of the fulcrum 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 R_a, our missing value, and plugging in our variables yields:

R_a = \( \frac{R_bd_b}{d_a} \) = \( \frac{65 lbs. \times 7 ft.}{4 ft.} \) = \( \frac{455 ft⋅lb}{4 ft.} \) = 113.75 lbs.