Name:______

Law of Conservation: Kinetic and Potential Energy

Directions:This sheet provides step by step practice problems for using the Law of Conservation to solve for energy problems.

- The Law of Conservation of Energy tells us thatTotal Energy = PE + KE

-What the Law of Conservation of energy means is that energy can transform (change) back and forth between Potential Energy and Kinetic Energy but the total energy always remains the same

1)Fill in the Blank. Energyinitial=______

2)How can we expand the equation from question 1 to help us solve for multi step energy problems? Fill in the blanks to see…

PEinitial+______= ______+ KEfinal

You can solve multistep energy problems using this equation, don’t get scared, you’ve done it before. Doesn’t this look the same as;

A + B =C + D

3)Let’s go even further in depth and see if we can use formulas we know to expand the equation from question 2 so that we can solve for multi step energy problems….. Fill in the blanks to see

[( ) ( ) (hinitial)] + [1/2 _____ vinitial2] = [( ) (g) (hfinal)] + [1/2m______]

Now we are ready to try a few practice problem….MAKE SURE TO SHOW ALL WORK

4)A 90kg man is clearing out his gutters and falls off his 3 storyroof which is 45 meters tall. He lands on his porch over hang which is 3 meters tall.

  1. Draw a diagram of this, label the 2 heights. place a star at the spot where the man has the most PE, draw a circle at the point where the man has less PE than what he started with but still has some remaining
  1. What is the man’s potential energy before he falls off his roof?

Remember: Total Energytop = GPEtop + KEtop

  1. What is the man’s Kinetic energy on roof before he falls?
  1. How do you know the answer to part c?
  1. What is the man’s PE when he hits the porch overhang?
  1. What is the man’s KE when he hits the porch overhang?
  1. what is the man’s velocity when he hits the porch over hang?

5) A 79kg mountain climber scales a mountain 1400 meters high. The climber gets a little carried away while celebrating at the top, loses his balance and falls 650 meters.

  1. Draw a diagram of this, label the 2 heights. place a star at the spot where the man has the most PE, draw a circle at the point where the man has less PE than what he started with but still has some remaining
  1. What is the mountain climber’s potential energy before he falls off the mountain

Remember: Total Energytop = GPEtop + KEtop

  1. What is the climbers KE at the top of the mountain before he falls?
  1. What is the mountain climbers PE at the bottom of the first fall?
  1. Whatis the mountain climbers KE at the bottom of the first fall?
  1. What is the mountain climbers velocity at the bottom of the second fall?

5)A 75kg woman drops her 25kg kayak in a river at the top of a waterfall totaling 105 meters in height. The waterfall is a double drop waterfall. The woman goes over the first drop which is 65 meters. She then goes over the second drop which is 40 meters .

  1. what is the woman’s PE at the top of the waterfall?
  1. What is the woman’s KE at the top of the waterfall?
  1. What is the woman’s PE when she lands the first drop?
  1. What is the woman’s KE right before she lands the first drop?
  1. What is the woman’s velocity when she lands the first drop?
  1. What is the woman’s Potential Energy at the bottom of the second drop?
  1. What is the woman’s KE at the bottom of the second drop?
  1. What is the woman’s velocity when she lands at the bottom of the second drop?

NOW WE ARE READY TO FINISH OUR ROLLER COASTER LABS