Agenda for 2/17/17 Potential and Kinetic Energy Notes Potential and Kinetic Energy Problems HW – none

Kinetic vs. Potential Energy

Potential Energy Potential energy is STORED energy due to position. Ex. A rock on top of a hill has a potential to do work.

Kinetic Energy Kinetic energy is the energy that a moving object has. Kinetic energy is energy that depends on MASS and VELOCITY (movement) If the rock is allowed to roll down the hill, then the potential energy is converted into kinetic energy.

Potential energy is stored energy—energy ready to go. A lawn mower filled with gasoline A car on top of a hill Students waiting to go home from school The light bulb not turned on Water stored behind a dam at a hydroelectric plant has potential energy. Kinetic energy is energy at work. A lawn mower cutting grass A car racing down a hill Students running home from school The light energy emitted by lamps. Even electrical energy is kinetic energy. Whenever we use energy to do work, it is in the kinetic state.

Conservation of Energy Kinetic Energy could then be converted back into potential energy. The energy can be split into Potential Energy and/or Kinetic Energy http://www.youtube.com/watch?v=Jnj8mc04r9E&feature=related

As potential energy decreases, the kinetic energy increases. As the potential energy increases, the kinetic energy decreases. http://www.youtube.com/watch?v=qZ4FFWvZtyo

No PE maximum KE right before he hits bottom  Lots of PE no KE  This also shows that energy is NOT being lost, just changing form! Equal PE and KE  No PE maximum KE right before he hits bottom 

FORMULAS Potential Energy = Mass x Gravity x Height Gravity = 9.8 m/s2 (Earth) Kinetic Energy = ½ Mass x Velocity2 The Units used are: Energy = Joules (J) Height = meters (m) Mass = kilograms (kg) Velocity = (m/s) Only square the velocity

Examples – Show work on back of notes What is the kinetic energy of a 2,000 kg boat moving at 5.0 m/s? K.E. = ½ m x v2 K.E. = ½ (2000) (5)2 K.E. = 25,000 J DON’T FORGET YOUR UNITS!

What is the gravitational potential energy of a ceiling fan that has a mass of 7 kg and is 4 m above the ground? P.E. = mass x gravity x height P.E. = (7) (9.8) (4) 274 J

A 1.0-kg ball is thrown into the air with an initial velocity of 30 m/s. a. How much kinetic energy does the ball have? K.E = 450 J b. How much potential energy does the ball have when it reaches the top at 60 meters high? P.E. = 588 J

Find the height of a baseball with a mass of 0 Find the height of a baseball with a mass of 0.15 kg that has a GPE of 73.5 J. PE = m x g x h 73.5 = 0.15 x 9.8 x h 73.5 = 1.47h 50 m = height

A jogger whose mass is 60 kg is moving at a speed of 3 m/s A jogger whose mass is 60 kg is moving at a speed of 3 m/s. What is the jogger’s kinetic energy? K.E = ½ mv2 K.E. = (0.5) (60) (3)2 K.E. = 270 J

Problem #1 What is the potential energy of a rock (on Earth) that has a mass of 100 kg that is sitting on top of a hill 300 meters high? 294,000 J

Problem #2 What is the kinetic energy of a bicycle with a mass of 14 kg traveling at velocity of 3.0 m/s? 63 J

Problem #3 A flowerpot with a mass of 500 grams is sitting on a windowsill 30 meters from the ground. Is the energy of the flowerpot potential or kinetic? How many joules in this? Potential energy 147 J

Problem #4 If a bowling ball has a mass of 10kg and is rolled with a velocity of 15 m/s, what is the ball’s kinetic energy? 1,125 J

Problem #5 A boulder is sitting on the top of a mountain. The boulder has a mass of 500 kg. The mountain is 1500 meters high. What is the boulder’s potential energy before it released? 7,350,000 J

Problem #6 A 1200 kg automobile is traveling at a velocity of 100 m/s. How much kinetic energy does it possess? 6,000,000 J

Agenda for 2/23/16 Go over homework New lab groups Kinetic Energy and Potential lab HW – none Quiz Thursday!

Lab Groups – Period 4 Station 1 – Griffin, Tyler, Emma, Maddie Station 2 – Aiden, Nolan, Caleb, Lauren, Adah Station 3 – Alex, Sam Glover, Anna, Landon, Jack Station 4 – Quinn, Reyan, Genevieve, Ella, Sophia W Station 5 – Sam, Connor, Riley, Sophia B

Lab Groups – Period 5 Station 1 – Rachel, Reese, Gavin, Sophia Station 2 – Ryan, James, Erin, Emma M Station 3 – Josh, Ben, Casey, Emily Station 4 – Miller, Christian, Emma T, Ally Station 5 – Tasha, Brendan, Justin, Schuyler, Jack