1. Introduction to Motion
Speed versus Velocity (scalar vs vector)
Speed from a Distance Time graph
Mathematical probs with motion
Converting units
Lets look at some motions
Speeding Velocities Homework problems

2. Speed vs Velocity
Speed is defined as distance over time (miles per hour or meters per second)
Speed describes how fast something moves.
Velocity describes how fast AND in what direction an object is moving.
Speed is a Scalar quantity, whereas Velocity is a VECTOR quantity.

3. Scalar vs. Vector Quantities
Scalar quantities show MAGNITUDE
Distance, Speed, etc.
Vector quantities show MAGNITUDE AND DIRECTION
Displacement, Velcocity, Acceleration, Force, Momentum, etc.

4. Speed from distance time graph
fastest
Distance (meters)
slowest
Time (seconds)

5. The slope of a distance time graph will give you speed
Rise (y2-y1)
Distance (meters)
Rise (y2-y1)
= speed
Slope =
Run (x2-x1)
Run (x2-x1)
Time (seconds)

6. Speed vs Velocity Speed Velocity 55 mph 55 mph North 70 m/s
70 m/s East
110 km/hr
110 km/hr West

7. Mathematical Probs with motion…..
Find the velocity in m/s of a swimmer who swims exactly 110 m toward the shore in 72 s ?
V=d/t = 110 m / 72 s = 1.5 m/s

8. Mathematical Probs with motion…..
Find the velocity in meters per second of a baseball thrown 38 m from 3rd base to 1st base in 1.7 seconds?
V=d/t = 38 m/ 1.7 s = 22 m/s

9. Mathematical Probs with motion…..
Calculate the distance in meters a cyclist would travel in 5.00 hours at an average velocity of 12.0 km/hr to the southwest?
D = V x t =(12.0 km/hr)(5.00 hr)
= 60 KM = meters

10. Mathematical Probs with motion…..
Calculate the time in seconds an Olympic skier would take to finish a 2.6 km race at an average velocity of 28 m/s downhill?
T = d/v = (2.6 km)(1000 m/km) = 93 s
28 m/s

11. Converting Units Convert 25 km/hr to m/s
25 km (1000m) (1 hr) = m/s
hr (1km) (3600 s)

12. Let’s look at motions on graphs !!!
Hint: Look at the slope!!!!
Slope tells us SPEED because
rise over run is speed on a
Distance-Time Graph.
Distance (meters)
Time (seconds)

13. Let’s look at motions on graphs !!!
Hint: Look at the slope!!!!
Slope tells us SPEED because
rise over run is speed on a
Distance-Time Graph.
Distance (meters)
Time (seconds)
Slope = velocity

14. Let’s look at motions on graphs !!!
Hint: Look at the slope!!!!
Slope tells us SPEED because
rise over run is speed on a
Distance-Time Graph.
Distance (meters)
Time (seconds)
Slope = velocity

15. Let’s look at motions on graphs !!!
Hint: Look at the slope!!!!
Slope tells us SPEED because
rise over run is speed on a
Distance-Time Graph.
Distance (meters)
Time (seconds)
Slope = velocity

16. Homework for Motion
In class: Let’s do Speeding Velocities (remember: sig figs counts)
Homework at home (Speeding Velocities)
Next time: acceleration and motion graphs. Scan info in Chapter 2 of your text.