1. 1. The (70˚ or 90˚)hill will give the bigger thrill because _____.
4*2 Gravitational Potential Energy and Kinetic Energy: What Goes Up and What Comes Down
WDYS? (p360) .
WDYT? (p360)
1. The (70˚ or 90˚)hill will give the bigger thrill because _____.

2. 4*2 Investigate (p360) As the distance increases,
Part A: What Affects the Speed of a Cart at the Bottom of a Ramp?
Keep the angle and height constant
a) Small d = b) Medium d = c) Large d =
As the distance increases,
the speed of the cart ________

3. the speed of the cart ________
4*2 Investigate (p360)
2. Now keep the distance constant
Small h = b) Medium h = c) Large h =
As the height increases,
the speed of the cart ________

4. 4*2 Investigate (p360)
3. Draw the picture from the WDYT? (p360)

5. 4*2 Investigate (p360)
The initial height of the car determines the final speed at the bottom of the ramp!!!

6. 4*2 TOTD
In your notes for 4*1, what are the 2 example of SCALAR quantities?
Displacement ONLY depends on _____.
If two carts are traveling at the same speed, but one cart only goes half the distance…what can you tell me about the time?
In one word, what produces the thrills on a roller coaster?
The speed of the ball increases with the increase of _____ and _____.

7. Physics Talk: Gravitational Potential Energy and Kinetic Energy (p363)
Energy Transformations in the Roller Coaster
The initial height of the cart determines how fast the cart travels at the bottom of the hill
Gravitational Potential Energy (GPE)  the energy an object possesses due to its position in a gravitational field; its dependent on the height of the object
EXAMPLE cart at the top of the slope

8. Physics Talk: Gravitational Potential Energy and Kinetic Energy (p363)
Kinetic Energy (KE)  energy an object possesses because of its speed
EXAMPLE cart moving to bottom of the slope
As the object comes down the incline, GPE decreases because the height above the ground decreases
In turn, its speed increases and its KE increases
**Therefore, GPE and KE are INVERSELY proportional**

9. Mechanical Energy  the sum of GPE and KE
ME = GPE + KE
***At ANY height you can determine the GPE and KE***
With your knowledge on energy conservation, you will be able to create an ENERGY BAR CHART 
***Remember during braking, some energy transforms into thermal energy, sound, and/or light ***

11. GPE = mass of object × gravity (10m/s/s) × height
GPE = (m×g)×h
GPE = W × h
***W eight = (m×g) is measured in (N)ewtons***

12. Example #1 (GPE):
A roller coaster with a mass of 500 kg is sitting at the top of a 10 m hill, if it’s not moving, what is its GPE?

13. Example #2 (mass):
What is the mass of a ball which is 2 m above the floor if its GPE is 1000 J?

14. Example #3 (GPE):
A boulder with a mass of 20 kg has 1000 J of GPE as it is sitting on the top of a ledge. How high is the ledge?

15. KE = ½ (mass of object × speed × speed) KE = ½ (m×v2)
KINETIC ENERGY!!!!
KE = ½ (mass of object × speed × speed)
KE = ½ (m×v2)
Joule (J)  the unit for energy

16. Example #4 (KE):
A roller coaster with a mass of 500 kg is Now at the bottom of the hill, its traveling at 14.1 m/s. What is it’s KE?

17. Example#5 (velocity):
A zombie is chasing you with a kinetic energy of 1500 J. Assuming it has a mass of 25 kg, how fast (minimally) should you run in order to stay alive?

18. Example #6 (KE):
A girl is roller skating at 5 m/s and has 500 J of energy. What is her mass?

19. Energy Equations
GPE = mgh m = GPE h = GPE = GPE (J) (kg) (g×h) (m) (m×g) weight KE =½(mv2) m = 2KE v =√2KE (J) (kg) v2 (m/s) m ***Joule (J)  the unit for EVERY energy***

20. Physics Talk: Gravitational Potential Energy and Kinetic Energy (p363)
2. Calculating KE from GPE
GPE + KE = constant
***If you know height, find GPE, and then KE***
3. Calculating Speed from KE and GPE
ME (bottom) = ME (top)
KE (bottom) = GPE (top)
v = √2gh

21. (don’t write questions—for 5 you’ll want the chart)
4-2 Checking Up (p367)
#1-5
(write the questions)
4-2 PTG p370
#1,2,5,7,9,10
(don’t write questions—for 5 you’ll want the chart)

22. PTG (p370)
Both cars will have _____ at the bottom because they both start _____.
KE = GPE =
mass =200kg
g = 10m/s/s
Height of car
GPE = mgh
KE = ½ (m×v2)
ME = GPE+KE
Top (30m)
Bottom (0m)
Halfway (15m)
¾ way (7.5m)

23. PTG (p370) 5. mass =300kg g = 10m/s/s Height of car GPE = mgh
KE = ½ (m×v2)
ME = GPE+KE
Top (25m)
Bottom (0m)
Halfway (12.5m)
¾ way (5m) 5.

24. PTG (p370)
7.a) GPE = b) KE = c) GPE = KE = 9. a) b) c) 10. a)

25. 4*2 TOTD 2
The __________of the cart determines how fast the cart travels at the bottom of the hill.
GPE is its dependent on _____ of the 1st hill.
GPE and KE are __________ proportional.
KE is fastest at the _____ of the slope.
ME = _____ + _____