1. TODAY
Today's Goal: 1) Lab In! 2) Finalize our understanding of ramps and FORCES. Homework: Given out. To make sure we can understand impulse through graphs and situations. HW Quiz next class

2. LAB
IN PLEASE

3. RAMP REVIEW
Instead of X and Y, we are going to rotate to a ‘New X’ and ‘New Y’:
‘New X’ : Down/Uphill
‘New Y’ : Perpendicular to the hill
Weight in X is the SIN of the weight.
Weight in Y (perpendicular to ramp) is the COS of the weight

4. Lets assume Its going downhill, and friction is present

5. Lets assume Its going uphill, and friction is present

6. AN EXAMPLE:
You and the cell phones.
You found the max angle it can be at before sliding. We will find the coefficient required for this.

8. So in this case, what is the relationship simplified to find the coefficient?
A) μ = sin θ F) μ = cot θ
B) μ = cos θ
C) μ = tan θ
D) μ = sec θ
E) μ = csc θ

9. No friction!
Assume M2 goes down + -

10. Which of these is true for the amount of imbalance in the system?
A) Its just W2 because the normal force on M1 cancels the weight
B) Its W2 + W1x, the system weight are them combined
C) Its W2 - W1x, the difference between the weights
D) Its W2 + W1, since system weight are them combined

11. Which of these is true for the amount of imbalance in the system?
A) Its just W2 because the normal force on M1 cancels the weight
B) Its W2 + W1x, the system weight are them combined
C) Its W2 - W1x, the difference between the weights
D) Its W2 + W1, since system weight are them combined

12. Assume friction of μ!

13. Which of these is true if m2 goes down AND friction is there?
A)(m1 + m2)a =m2g–m1gcosθ –μm1gsinθ
B)(m1 + m2)a =m2g–m1gcosθ +μm1gsinθ
C)(m1 + m2)a =m2g–m1gsinθ –μm1gcosθ
D)(m1 + m2)a =m2g–m1gsinθ +μm1gcosθ

14. Which of these is true if m2 goes up AND friction is there?
A)(m1 + m2)a =m2g–m1gcosθ –μm1gsinθ
B)(m1 + m2)a =m2g–m1gcosθ +μm1gsinθ
C)(m1 + m2)a =m2g–m1gsinθ –μm1gcosθ
D)(m1 + m2)a =m2g–m1gsinθ +μm1gcosθ

15. LETS TRY SOME HW!

16. MOMENTUM AS AN IDEA:
The AMOUNT of ‘motion’ something has.
The more MOMENTUM something has, the harder it is to change the objects VELOCITY

17. MOMENTUM is represented by the letter P.
P = mv and direction matters! You can have + and – amounts, it represents DIRECTION

18. For example, a 1500kg car is going LEFT at 10m/s.
And a 2000kg car is going RIGHT at 8m/s.
How much momentum does each one have?

19. AND HOW MUCH MOMENTUM IS IN THE SYSTEM OF BOTH CARS?

20. And if they hit and combine, which way do you think the combined wreck will move? Left or Right?

21. SO IN AN ISOLATED SYSTEM:
The total amount of momentum before and after an event is the same!

22. Momentum : Its like the overall motion of an object. Has direction.
Idea
In Words
In Equation
Units
How its used
Momentum, Symbol is p
The motion of objects which involves both the mass and velocity.
p = m*v
Kg*m/s or a N*s
In systems where two objects interact, momentum is conserved
Momentum : Its like the overall motion of an object. Has direction.

23. Two Things Hitting: So lets ask…
1) Where does the car get the momentum to move from?
The TRUCK! The truck LOSES some momentum which the car gains

24. Two Things Hitting: So lets ask…
2) How does the change in momentum of the heavy truck compare to that of the car?
They are the same! Due to the conservation of momentum of this isolated system.

25. Two Things Hitting: So lets ask…
3) How does the change in velocity of the heavy truck compare to that of the car?
The truck (which is heavier) will have less of a change in velocity from the same change in momentum (due to larger inertia)

26. Two Things Hitting: BEFORE THE IMPACT:
How much momentum does the truck and car have?
TRUCK CAR

27. Two Things Hitting: AFTER THE IMPACT:
How much momentum does the truck and car have?
TRUCK CAR

28. Two Things Hitting:
LETS MAKE A TABLE TOGETHER

29. Two Things Hitting:
Lets graph the change in velocity for each!

30. IN SUMMARY SO FAR:
Momentum is the ‘motion of an object’ p = mv.
It is transferred between things
In an isolated system, the system amount wont change, just redistributed