Today’s Agenda
11/12
Planning Ahead…
Due This Week
3.09
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Optional Video:
Conservation of Energy
https://www.pbs.org/video/segment-4h-conservation-of-energy-6shoa3/
WEEK 20
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WEEK 17
WEEK 16
WEEK 15
WEEK 14
INTRO
WEEK 1
WEEK 2
WEEK 3
WEEK 4
WEEK 5
WEEK 7
WEEK 13
WEEK 12
WEEK 11
WEEK 10
WEEK 9
WEEK 8
WEEK 6
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3.09: Conservation of Energy
In 3.07, we focused on KE and GPE. However, energy exchanges can go beyond KE and GPE.
Work Energy Relationship:
We now state that the total energy within a closed system is equal to the sum of the kinetic energy, potential energy, and internal energy.
Etotal = KE + PE + Q
No Friction: (Conservative)
(GPE + KE)top = (GPE + KE)bottom
Friction: (Non-Conservative)
(GPE + KE)top = (GPE + KE + Q)bottom
Parts of the equations may be zero depending on the givens.
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WEEK 10
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WEEK 7
INTRO
WEEK 1
WEEK 2
WEEK 3
WEEK 4
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WEEK 6
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Example 1
The 66 kg skateboarder starts from rest at the top of the ramp. At point C, the skater is moving at 6m/s.
How much potential energy was converted to thermal energy (heat)?
No Friction: (Conservative)
(GPE + KE)top = (GPE + KE)bottom
Friction: (Non-Conservative)
(GPE + KE)top = (GPE + KE + Q)bottom
Step | Work |
Givens | |
Unknown | |
Decide on Equation | |
Substitution & Solution | |
| |
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WEEK 13
WEEK 12
WEEK 11
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WEEK 9
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WEEK 7
INTRO
WEEK 1
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WEEK 6
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Example 2
The 66 kg skateboarder starts from rest at the top of the ramp. How fast is the skateboarder moving at the lowest point of the ramp (point B). A new ramp was built that is super smooth so, ignore any effects of friction.
No Friction: (Conservative)
(GPE + KE)top = (GPE + KE)bottom
Friction: (Non-Conservative)
(GPE + KE)top = (GPE + KE + Q)bottom
Step | Work |
Givens | |
Unknown | |
Decide on Equation | |
Substitution & Solution | |
| |
WEEK 20
WEEK 19
WEEK 18
WEEK 17
WEEK 16
WEEK 15
WEEK 14
WEEK 13
WEEK 12
WEEK 11
WEEK 10
WEEK 9
WEEK 8
WEEK 7
INTRO
WEEK 1
WEEK 2
WEEK 3
WEEK 4
WEEK 5
WEEK 6
SLIDESMANIA.COM
3.09: Hooke’s Law and More!
Situation | Relationship or Variable | Equation |
Stretch | Hooke’s Law | F = k Δ x |
Energy due to stretch | Elastic Potential Energy | EPE = ½ k x^2 |
Stress over Strain | Young's Modulus | Y = (F/Acs)/(Δ L/Lo) |
Strength of Material | Tensile Strength | Tensile Strength = F / A |
Surface Tension | Gamma | ----- |
The primary focus of lesson 3.09 is conservation of energy and related calculations. However, also practice Hooke’s Law and springs in general.
WEEK 20
WEEK 19
WEEK 18
WEEK 17
WEEK 16
WEEK 15
WEEK 14
WEEK 13
WEEK 12
WEEK 11
WEEK 10
WEEK 9
WEEK 8
WEEK 7
INTRO
WEEK 1
WEEK 2
WEEK 3
WEEK 4
WEEK 5
WEEK 6
SLIDESMANIA.COM
3.09: Hooke’s Law and More!
The primary focus of lesson 3.09 is conservation of energy and related calculations. However, also practice Hooke’s Law and springs in general.
Givens | m = x = |
Unknown | k =? |
Equation | F = kx |
Substitution | |
Solution | |
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WEEK 14
WEEK 13
WEEK 12
WEEK 11
WEEK 10
WEEK 9
WEEK 8
WEEK 7
INTRO
WEEK 1
WEEK 2
WEEK 3
WEEK 4
WEEK 5
WEEK 6
SLIDESMANIA.COM
3.09: Hooke’s Law and More!
The primary focus of lesson 3.09 is conservation of energy and related calculations. However, also practice Hooke’s Law and springs in general.
Givens | m = 0.050 kg x = 0.07 m |
Unknown | k |
Equation | F = kx |
Substitution | (0.050)(9.8) = k (0.07) |
Solution | k = 7 N/m |
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WEEK 18
WEEK 17
WEEK 16
WEEK 15
WEEK 14
WEEK 13
WEEK 12
WEEK 11
WEEK 10
WEEK 9
WEEK 8
WEEK 7
INTRO
WEEK 1
WEEK 2
WEEK 3
WEEK 4
WEEK 5
WEEK 6
SLIDESMANIA.COM
3.09: Hooke’s Law and More!
The primary focus of lesson 3.09 is conservation of energy and related calculations. However, also practice Hooke’s Law and springs in general.
WEEK 20
WEEK 19
WEEK 18
WEEK 17
WEEK 16
WEEK 15
WEEK 14
WEEK 13
WEEK 12
WEEK 11
WEEK 10
WEEK 9
WEEK 8
WEEK 7
INTRO
WEEK 1
WEEK 2
WEEK 3
WEEK 4
WEEK 5
WEEK 6
SLIDESMANIA.COM