1. Physics Review
Chapters 1 – 3
C. Buttery
9/16/16

2. overview Vectors & Vector Addition Kinematics in 1D Kinematics in 2D
Newton’s Laws (if time)

3. Vectors Vectors can only be added tip to tail
The resultant vector is drawn from the tail of the first to the tip of the last
Remember trig functions! SOH CAH TOA
Also Pythagorean Theorem: 𝑎 2 + 𝑏 2 = 𝑐 2
Vectors can be moved anywhere, typically drawn from the origin and then moved
Also remember scalar vs vector: speed, distance are scalars; velocity, displacement, acceleration, vectors

4. Practice problems

5. Practice Problems

6. Kinematics in 1D Five Kinematic Variables: 𝑥 (or 𝑦) displacement
𝑎 acceleration
𝑣 or 𝑣 𝑓 final velocity
𝑣 𝑜 or 𝑣 𝑖 initial velocity
𝑡 elapsed time
Velocity, displacement, and acceleration are either positive or negative

7. Kinematics in 1D Three equations to know how to use: 𝑣= 𝑣 𝑜 +𝑎𝑡
𝑣 2 = 𝑣 𝑜 2 +2𝑎𝑥
𝑥= 𝑣 𝑜 𝑡+ 1 2 𝑎 𝑡 2
Also these are useful as well:
𝑣 𝑎𝑣𝑔 = Δx Δ𝑡
𝑎= Δ𝑣 Δ𝑡

8. Kinematics in 1D Tips for solving problems: Draw a picture!
Decide which direction is positive and which is negative
Write down what you have in terms of each variable
All you need is 3 of the 5 variable to solve for any 4th
There may be multiple ways to get the same answer
Remember if a problem is divided into segments, the final velocity for one section could be the initial for another

9. Practice Problems

10. Practice Problems

11. Practice Problems
Answer:
𝑥=4.5𝑚

12. Practice Problems

13. Practice Problems
(this is 1.6 𝑚/ 𝑠 2 )

14. Kinematics in 2D Works almost the same as kinematics in 1D
Same equations
Directions are independent of each other
Time is usually the same across both x and y directions

15. Kinematics in 2D Three important things to remember: 𝑎 𝑥 =0
Therefore, 𝑣 𝑜𝑥 = 𝑣 𝑓𝑥
𝑎 𝑦 =10 𝑚/ 𝑠 2 or 9.8 𝑚/ 𝑠 2
Basically, gravity
If finding max height, 𝑣 𝑓𝑦 =0

16. Practice Problems

17. Practice Problems
Answer:
𝐷=3.4 𝑚

18. Practice Problems

19. Practice Problems

20. Practice problems Answer: 𝑣 𝑜 =45.5 𝑚/𝑠
So in other words, not possible.

21. Forces and Newton’s Laws
Newton’s Laws (abridged)
1st: An object continues at a constant velocity or at a state of rest until a force acts on it
2nd: 𝐹=𝑚𝑎
3rd: Equal and opposite reactions

22. Forces and Newton’s Laws
Types of forces:
Normal Force – perpendicular to a surface
Weight – mass times gravity
Tension – along a rope
Friction – either static or kinetic, opposes motion
𝐹 𝑓 = 𝜇 𝑓 𝑁
Centripetal (think chapter 5)

23. Forces and Newton’s Laws
Remember that every force can be written as 𝐹=𝑚𝑎
Sum your forces in both 𝑥 and 𝑦 directions separately
0<𝜇<1
Normal force isn’t necessarily equal to weight
Draw your free body diagrams!
What constitutes equilibrium and what will have a net force

24. That’s It! Questions, comments, concerns, more problems?
Make sure you study and practice over the weekend
Good luck!