This is my PowerPoint One.

2.  Mechanics- Study of Motion
 Kinematics- Mechanics of Objects
**Assume no rotation**
 Ex. Cars, Atoms, Planes

3.  Position Vector – Where it is
 Denoted by: r
 Changes as a function of time
 r = r (t)

4.  Definition: Difference between final
position vector and initial position vector
 Δr = r2 – r1
 Δr means “difference or change in”

5. **Not the same as Displacement**
 Recall displacement- how far from origin
 Definition: Absolute value of the displacement
vector
 “How far you’ve traveled”
 Δr = |r1| + |r2|

6.  Your dorm room is located 0.25 mi from the dairy
store. You walk from your room to the Dairy Store and
back. Which of the statements is true:
a) The distance is 0.5 mi and displacement is 0.5 mi.
b) The distance is 0.5 mi and displacement is 0.0 mi.
c) The distance is 0.0 mi and displacement is 0.5 mi.

7. Home Dairy Store
0.25mi
Displacement = Δr = r2 – r1 = 0.25 – 0.25 = 0mi
Distance = Δr = |r1| + |r2| = |0.25| + |0.25| = 0.5mi

8.  If ri = rf, displacement is 0.
Displacement = How far from origin
Distance = Total ground covered

9.  Average velocity – Vx =
Δ푥
Δ푡
 Instantaneous velocity – V =
푑푟
푑푡
 Speed – absolute value of velocity
 Velocity – a vector with direction
**Speed is never negative**

10. Speed = |v| = |vx|
Average speed = v =
푙
Δ푡
“푙” being distance

11. Suppose a swimmer completes the first
50m of the 100m freestyle in 38.2s. She
then turns around and swims back in 42.5s.
Question: What is the average velocity and
average speed for the first leg?

12. Vx =
Δ푥
Δ푡
=
푥2 − 푥1
Δ푡
=
50푚 −0푚
38.2푠
= 1.31푚
푠
Average velocity = 1.31푚
푠
Speed is the absolute value = |1.31| = 1.31

13. Average acceleration – defined as the
velocity change per time interval
 ax =
Δ푉푥
Δ푡
Instantaneous acceleration – defined as
the limit of the average acceleration as the
time interval approaches 0.

14. Average
Velocity/Acceleration
Instantaneous
Velocity/Acceleration

15. I. 푥 = 푥0 + 푉푥0푡 +
1
2
푎푥 푡2
II. 푥 = 푥0 + 푉푥 t
III. 푉푥 = 푉푥0 + 푎푥 푡
IV. 푉푥 =
1
2
푉푥 + 푉푥0
2 = 푉푥0
V. 푉푥
2 + 2푎푥 (푥 − 푥0)

16. Assuming a constant acceleration
of ax = 4.3 m/s2, starting from rest,
what is the airplane’s take off
velocity after 18.4s?

17. I. 푉푥= 푉푥0 + 푎푥 푡 Find an equation
II. 푉푥0 = 0, At Rest
III. 푎푥 = 4.3푚
푠 Acceleration
IV. 푡 = 18.4푠 Time
V. 푉푥 = 4.3 푚
푠 18.4푠 = 79.12 푚
푠

18.  Displacement – how far from origin
 Distance – how far you’ve traveled
 Velocity – vector with direction
 Speed – absolute value of velocity
 Acceleration – velocity change with time

19. • Campus Party Brasil, “Michio Kaku” February
11, 2012 via Flickr, Attribution-ShareAlike
• Ed Schipul, “Bill Nye” October 21, 2010 via
Flickr, Attribution-ShareAlike
• Bauer, W., & Westfall, G. (2014). University
physics (Second ed.). New York, NY: McGraw-
Hill.