Unit 8 Post - 7/08: Work and Energy

Today we learned about work and energy. I always thought work meant putting effort into something; for example we had someone holding heavy boxes and I thought that was work because of the fact that it required effort and energy to do! It's not like he could've just held those boxes for the rest of his life! But in physics sense, work is a change in energy: Work = Force X Distance (joules)
Work only happens when you're working against a force, so if its a frictionless environment then work is impossible. But if your working against gravity or some form of friction then your have to put in WORK!

Energy isn't created or lost, it simply changes form - this is the law of conservation of energy. The two main forms of energy we're exploring are kinetic energy (motion) and potential energy
Potential Energy is calculated by weight X height. You can think of it as the amount of energy "stored" in the object with the potential to release. When that energy is released, it changes into kinetic energy!
Kinetic energy is basically the energy of motion! The total energy of your system stays the same so as kinetic energy decreases, potential energy increases and vise-versa. They have an inverse relationship.

In this picture, the fact that I'm standing at an altitude that is higher than my equilibrium (the ground) means I have potential energy.
PE = mgh (potential energy = mass X acceleration of gravity X height)
PE = 55.79 kg X 9.8 m/s^2 X 0.64 meters
My potential energy = 349.91 Joules

In this picture I am falling with kinetic energy. I simply stepped off the bench to release my potential energy and change it to energy of motion.
KE = 1/2MV^2 (kinetic energy = half of the mass X velocity squared)
KE = 1/2(55.79 kg)(assumed velocity of 0.5 m/x)^2
My kinetic energy = 6.97 Joules