1. Chapter 3
Linear Motion

2. Description of Motion -Kinematics
Average Speed = total distance/time
Total distance = (Average speed) x (time)

3. Velocity Speed in a particular direction Examples
70mi/h due north --- is a velocity
70mi/h is a speed

4. Approximate Speeds in Different Units
20km/h
12 mi/h
6 m/s
40 km/h
25 mi/h
11 m/s
60 km/h
37 mi/h
17 m/s
65 km/h
40 mi/h
18 m/s
80 km/h
50 mi/h
22 m/s
88 km/h
55 mi/h
24 m/s
100 km/h
62 mi/h
28 m/s
120 km/h
75 mi/h
33 m/s

5. Velocity is proportional to the time

6. Acceleration
Acceleration = change in velocity/change in time

7. Constant Acceleration – Free Fall
Near the surface of the earth, all objects fall with the same acceleration baring effects from air friction.
In this case, a = g = 9.8m/s/s or 32 ft/s/s
or a = g = 9.8m/s2 or 32 ft/s2

8. Distance traveled Assume a= 2 m/s/s and is constant. 4m 1m 9m 1 sec

9. The distance traveled is proportional to the time squared.

11. Distance vs time d = ½ gt2

12. If a is constant

13. If the particle starts with an initial velocity of Vo at zero seconds (to = 0 sec) then:

14. Assume Vo = 1m/s and a = 10m/s2
t(sec)
V(m/s)
0 s
1 m/s
1 s
11 m/s
2 s
21 m/s
3 s
31 m/s
4 s
41 m/s
5 s
51 m/s
6 s
61 m/s
7 s
71m/s
8 s
81 m/s
9 s
91m/s
10 s
101 m/s
Assume Vo = 1m/s and a = 10m/s2

15. For free-fall