Mechanics II

Translational Equilibrium

A body is in translational equilibrium when the vector sum of forces acting on it is zero. As a result, the body stays in one location.
Moments
Moment (or torque) = F x perpendicular distance to pivot point

Rotational Equilibrium
A body is in rotational equilibrium when the sum of clockwise moments = sum of counter-clockwise moments. As a result, the body does not rotate.
Momentum
Momentum = mv

Momentum is a vector quantity, meaning it has direction as well as magnitude.

Law of Conservation of Momentum
Smv before collision = Smv after collision

Elastic and Inelastic Collisions
In an elastic collision, KE is conserved. In an inelastic collision, some or all of the KE is converted to sound, light, heat, and so forth.

Impulse
Impulse = change in momentum
= D(mv)
= mDv

Since F = ma = mDv/t
mDv = Ft
or impulse = Ft

Potential Energy (PE)
PE = mgh

Kinetic Energy (KE)
KE = ½mv²

Work
Work done = Fd

Where F is force and
d is distance

Power

Power is the rate at which work is done

Power = Fd/t = Fv