Bell Ringer Why are you at school? What are you going to do today to relieve your stress? What can you do to make today more meaningful?

Mechanical Energy

What we want from the lab… What is energy? How is energy stored? Where is energy stored? What does energy do? Where does energy go? How is energy transferred?

Energy is an objects ability to do work! The units we use for energy are joules (J) Energy may exist many different forms: potential, kinetic, thermal, electrical, chemical, nuclear, or other various types.

Gravitational Potential Energy Energy given to an object because of gravity 𝑈 𝑔 =𝑚𝑔ℎ 2750 𝐽 55 m 50 m 2500 𝐽 1000 𝐽 20 m The amount of gravitational energy something has is relative!!!!! 3 kg How much energy does the slab of bacon have relative to the table? The floor? 0 𝐽 5kg 1𝑚 0 m 0 𝐽 30 𝐽

Kinetic Energy Energy of MOTION!!!!!! Anything that is moving has kinetic energy!!! 𝐾 𝐸 = 1 2 𝑚 𝑣 2 If the baseball (0.14kg) leaves the pitcher’s hand moving 50 m/s, how much kinetic energy does it have? 𝐾 𝐸 = 1 2 (0.14) (50) 2 𝐾 𝐸 =175 𝐽

Spring/Elastic Energy 𝑈 𝑆 = 1 2 𝑘 𝑥 2 k is the spring constant, the larger the number the stronger the spring. Unit=(N/m) x is the distance the spring is either stretched or compressed

Practice If Jane can store 435 J of energy in the ballista’s spring, how far back will she be able to pull the bowling ball if the spring constant is 7 N/m? 𝑈 𝑆 = 1 2 𝑘 𝑥 2 435= 1 2 (7) 𝑥 2 x=11.1𝑚

Chemical Energy Electrical Thermal Nuclear Magnetic potential Electric potential