Energy Lab page 73 Height 2 books Height

Energy Lab: page 73 Height (2 books) Height (3 books) Height (4 books) Mass of Marble (Kg) Length of ramp (m) Height of ramp (m) Time (s) Average Speed (m/s) Final Speed (2 x Average speed) (m/s) Final Kinetic Energy (J) Initial Potential Energy (J) Initial PE – Final KE (J)

Energy Lab Questions: page 72 1)Compare the PE and the KE for each height. 2)How did the PE change with height? 3)How did the KE change with height? 4)Make a double bar graph with PE on the Left and KE on the right.

Energy Page 75

Energy and work • Whenever work is done, energy is transformed or is transferred from one system to another system. • Work is only done when an object moves, but energy can be present when an object is at rest or moving. • The amount of energy transferred can be measured by the amount of work done. • Energy is the ability to do work, so it is also measured in joules (J).

Potential Energy (PE) • Energy of position, results from the relative position of objects in a system. • Stretched/compressed: • Distance increased or decreased: • Gravitational potential energy: depends on mass and height. • PE=mgh

Kinetic Energy (KE): • The energy an object has because of its movement. • Depends on both the mass and the speed of an object. • KE= ½ mv 2 • The unit for KE is also joules (J). • Because the velocity is squared the speed has more influence then the mass. • Atoms and molecules are always moving, therefore have KE. (temperature).

Other forms of Energy • Mechanical Energy: the combination of an object PE and KE. • Chemical potential energy: depends on the relative position of atoms in a molecule. Energy is released when the bonds are broken. • Photosynthesis: Turns sunlight into chemical energy. • Respiration: Turns stored chemical energy into ATP. (energy your body can use). • Nuclear energy: Fission (splitting atoms) Fusion (combining atoms).

Energy Review Questions: page 74 1) 2) 3) 4) List 3 forms of energy. Explain how energy differs from work. Make a Venn Diagram of Potential Energy and Kinetic Energy? Identify the form of energy for each: a) A Frisbee flying in the air. b) A boulder on top of a cliff. c) A wound clock. d) An apple. 5) Calculate the gravitational potential energy of a 93 Kg sky diver who is 550 m above the ground. 6) Calculate the Kinetic Energy of a 0. 02 Kg bullet traveling 300 m/s.