Physics Unit 8

In class, we learned about energy and work. We learned about the different types of energies and how to find them. We also learned about the Law of Conservation of Energy, which states that energy cannot be created or destroyed, it only changes form. Energy is a scalar quantity, which means his has magnitude but no direction. We also learned about joules, which is the unit you would use for energy, and is found by multiplying the object's force (newtons) with its height (meters).

There are three types of energy (that we learned about):

Kinetic energy = energy of motion. Temperature is a measure of average kinetic energy.
Its equation is KE = 1/2 x mass x (velocity)^2 = 1/2mv^2.
The picture on the left is my Jack Russell Terrier, Abby. So, using the equation, if she had a mass 8kg, and a velocity of 2m/s, her kinetic energy would be 16 Joules.













Spring potential energy = the potential energy in a spring (its name speaks for itself). Its equation is PEs = 1/2 x spring constant x (the distance the spring is stretched/compressed)^2 = 1/2kd^2. In order to find the spring constant, you would use the slope of a Force vs. Time graph.  The picture on the left is of a rubberband and a spring, both of which have spring potential energy when they are either stretched or compressed.

Potential (gravitational) energy = the potential energy of an object (once again, it's name speaks for itself). Its equation is PEg = mass x (acceleration of) gravity x change in height = mgh. The picture on the left is of my deodorant                   (ew, deodorant) about to jump off my dresser, which is about a meter tall. If my deodorant has a mass of 1kg, and yes, we are on Earth, then my deodorant's potential gravitational energy is 9.8 Joules.











Some extra equations we learned are:
Hooke's Law = Force of spring = -kd. K is the spring constant, and d is the distance that it is stretched or compressed. The negative in front of the k is to show which direction the spring is being pulled/pushed. This equation doesn't actually have to do with energy, but is still useful.
Work = change in energy = force x distance.