# List of formulas related to Work and energy

#### Work

W: work done by a force (j), F: force move a object for a distance s, α: angle between F and movement direction

$$W = Fs \cos\alpha$$

#### Example

Wp: work by gravity, h: the change in height; wms:work of friction’s force; W: work by a spring

$$W_p = mgh$$ $$W_{ms} = - F_{ms}.s$$ $$W = \frac{1}{2}k(x_1^2 -x_2^2)$$

#### Power

P: power (watt, W), t: time of conducting the work W(s)

$$p = \frac{W}{t}$$

#### Kinetic Energy

$$E_k = \frac{1}{2}mv^2$$

#### Kinetic Energy Of A Massive Rotating Body

$$E_K = \frac{1}{2}Iw^2$$

#### Work Energy Principle

v1, v2: speeds of object before and after the change

$$W = \Delta E_k = \frac{1}{2}mv_2^2 - \frac{1}{2}mv_1^2$$

#### Potential Energy

Ep: gravitational potential energy (j), m: mass of object (kg)

$$E_p = mgh$$

#### Conservation of Mechanical Energy

$$E_k + E_p = constant$$

#### Conservation Of Energy

$$E_k + E_p + E_c + ...= constant$$