(Wed/Thur: Jan 14th/15th):

 

Key Concept's) Today: Lab KE --> PE

 

Journal: An 400kg car is moving at 10m/s on a flat highway and then put into neutral so that it coasts to stop. If the car started with 40,000 J of KE, then where did all the energy go if "Conservation of Energy" is a Law?

 

 

 

Lab: Potential Energy à Kinetic Energy

 

  • Question: How far will an object travel given a certain amount of Potential Energy?

 

  • Background:        PE = mgh         KE =1/2 mv2   

  • Vertical falling distance:  x = Vot  + 1/2 at2          Horizontal Distance:   x  = vt

  1. Find Horizontal Velocity of bob

  2. Find time it takes for the bob to hit the floor   (2nd height)

  3. Calculate the Horizontal Distance and make mark on floor

 

 

 

 

 

       h1

                                                        cut

                                                        

 

                                                          h2

 

 

 

         

                                                                X

 

 

  • Hypothesis: If the height of the bob (pendulum) is __________ m above the bottom of the arc and the height of the arc is _____ m above the floor, then the bob will travel ____ m horizontal when cut (at the bottom of the arc) because both the horizontal velocity at the bottom of the arc and time to hit the ground based on its height can be calculated.

 

  • Materials: ring stand, thread, bob and razor blade.

  • Procedures (Yours: 4-7 numbered steps):

         

  • Data:                         

           

Height above arc (m)

  

Horizontal Velocity (m/s)

Height above ground (M)

Time to hit ground (s)

Horizontal Dist (x) traveled

 

 

 

 

 

 

 

 

 

  • EC:    If you can land within 2.0 cm of your predicted target.

 

  • Conclusion:  (use Data to support)

Analysis:

1. Was Hypothesis correct?

2. % error (show work)

3. Why were you off?

4. 3 ways to have more valid result