5.2 Energy

- Energy is the ability to do work.

- The amount of energy transferred to an oobject equals the work done and when an object does work it loses an equal amount of energy.

- There are three broad categories of enerrgy:

1. ) Kinetic energy - The energy something possesses by virtue of its motion.
   
   
2. ) Potential energy - The energy something possesses by virtue of its position.
   
   
3. ) Rest energy - The energy something possesses by virtue of its mass. E = mc²

- An object's kinetic energy is proportionnal to the mass of an object and also the square of the velocity of an object.

KE = 1/2 mv²

- Increasing the amount of work done on ann object also increases the kinetic energy.

W = Fx = max = m v²/2 = KE

- An object's gravitational potential enerrgy is proportional to the mass of an object and also the height of an object.

PE = mgh

- Increasing the amount of work done on ann object also increases the potential energy.

W =F_gy = mgh = PE

- Elastic potential energy can be stored iin an object that has changed its shape.

- By using the spring constant k we can deetermine a spring's elastic potential energy as:

PE_elast = 1/2 kx²

- According to Hooke's Law the spring consstant "k" can found by applying a force and dividing it by the displacement from equilibrium, "x" that was created.

k = F/x