PHYS 110 Lab #8: Energy II
In this lab you will be practicing creating and applying energy models for several different scenarios.
1. Happy Ball
Drop the happy ball onto the table top. We are interested in the energy of the ball from the instant you let it go un?l the highest point it reaches aHer one bounce. Well also inves?gate the moment of impact with the table.
The big idea: Applying energy models
Sketch the scenario iden?fying the system, the zero reference point, and ini?al and final points of interest:
As the ball falls, does the gravita?onal poten?al energy increase, decrease or stay the same?
As the ball falls, does the kine?c energy increase, decrease or stay the same?
On the way up (aHer the bounce), does the poten?al energy increase, decrease or stay the same?
On the way up (aHer the bounce), does the kine?c energy increase, decrease or stay the same?
What is the kine?c energy at the moment of impact with the table?
What is the gravita?onal poten?al energy at the moment of impact with the table?
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Does the ball have some other energy at the moment of impact with the table? If yes, how do you know and how is the ball storing the energy? [Hint: is the ball squishy?] If no, explain why not.
LOL diagram (ini?al drop and impact with table):
Energy Model (equa?on) (for the ini?al drop and impact with the table):
Will energy be conserved? (i.e., does ?Esys =0?)
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Name:
Now youll repeat the analysis with the ini?al drop and the final height that the ball reaches.
LOL diagram (ini?al drop and final height):
Energy Model (equa?on) (for ini?al drop and final height):
Will energy be conserved? (i.e., does ?Esys =0?)
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2. Projectile #1: Tennis Ball Drop
Drop a tennis ball onto your partners hand from different heights. We are interested in the energy of the ball from the instant you let it go un?l it lands in your partners hand.
Sketch the scenario iden?fying the system, the zero reference point, and ini?al and final points of interest:
AHer impact on the hand, when the ball has landed on the hand, is the kine?c energy zero (Yes/No)?
If yes, where did the balls energy go?
Is the gravita?onal poten?al energy greater, smaller or the same when it is held at a higher loca?on?
LOL diagram:
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Name:
3. Sad Ball
Drop the sad ball onto the table top from the same height you used for the happy ball. We are interested in the energy of the ball from the instant you let it go un?l impact with the table.
Energy Model (equa?on):
Will energy be conserved? (i.e., does ?Esys =0?)
QUESTION 1: When dropped from a higher loca?on, is the kine?c energy (right before hi^ng the hand) bigger or smaller than when dropped from the original height? Explain.
Sketch the scenario, identifying the system, the zero reference point, and initial and final points of interest:
What is the kine?c energy at the moment of impact with the table?
What is the gravita?onal poten?al energy at the moment of impact with the table?
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Does the ball have some other energy at the moment of impact with the table? If yes, how do you know and how is the ball storing the energy? [Hint: is the ball squishy?] If no, explain why not.
Does the ball transfer energy to the table? (Yes/No)
If your answer was YES: If your answer was NO:
How do you know energy was transferred to the table?
How do you know energy was not transferred to the table?
Did it transfer the energy by doing work? Explain.
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Name:
LOL diagram:
Energy Model (eqn):
Will energy be conserved? (i.e., does ?Esys =0?)
QUESTION 2: Whats the difference between the happy and sad balls, in terms of how they store or release poten?al energy?
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4. Projectile #2: Horizontal Throw of Tennis Ball
Throw a tennis ball horizontally & let it hit the floor. We are interested in the energy from the moment just before you start to throw it un?l the moment just before its impact on the floor. (You can ignore the any bouncing or rolling.)
Sketch the scenario, iden?fying the system, the zero reference point, and ini?al and final points of interest:
Before the throw, is the kine?c energy zero? (Yes/No)
AHer the throw, is the kine?c energy zero? (Yes/No)
During the horizontal throw, does the gravita?onal poten?al energy increase, decrease or stay the same?
QUESTION 3: Did you do work on the ball? If yes, did you give or take energy from the ball? If no, explain why you did not do work.
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Name:
5. Projectile #3: Catching a Ball
Throw a tennis ball to one of your partners. We are interested in the energy from the moment you start to throw it to the moment the ball is at rest in your partners hand.
Pay aden?on to the movement of your hand as you throw and the movement of their hand when they catch the ball; also note the height of your hand and the height of their hand.
LOL diagram:
Energy Model (eqn):
Will energy be conserved? (i.e., does ?Esys =0?)
Sketch the scenario, identifying the system, the zero reference point, and initial and final points of interest:
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Before the throw, is the kine?c energy zero? (Yes/No)
AHer the catch, is the kine?c energy zero? (Yes/No)
Did you do work on the ball? If yes, did you give or take energy from the ball? If no, explain why you did not do work.
Did your partner do work on the ball? If yes, did your partner give or take energy from the ball? If no, explain why your partner did not do work.
LOL diagram:
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