1. Speed and Velocity

2. Speed
The ratio of the distance an object moves to the amount of time the object moves
SI units for speed is meters per second (m/s)
Large speeds km/h

3. Average Speed
Total distance traveled divided by the time it takes to travel that distance
Average speed is computed for the entire duration of a trip

4. Formula

5. Speed 5 s 4 s 1 s 2 s 3 s A car drives 100 meters in 5 seconds.
What is the car’s average speed?
s = d/t
s = (100 m) / (5 s) = 20 m/s
100 m
5 s
4 s
1 s
2 s
3 s

6. Calculating Average Speed
While traveling on vacation, you measure the times and distances traveled. You travel 35 kilometers in 0.4 hour, followed by 53 kilometers in 0.6 hour. What is your average speed?

7. Calculating Average Speed
A person jogs 4.0 kilometers in 32 minutes, then 2.0 kilometers in 22 minutes, and finally 1.0 kilometer in 16 minutes. What is the jogger’s average speed in kilometers per minute?

8. Calculating Average Speed
A train travels 190 kilometers in 3.0 hours, and then 120 kilometers in 2.0 hours. What is its average speed?

9. Instantaneous Speed
Rate at which an object is moving at a given moment in time
Instantaneous speed is measured at a particular instant

10. Graphing Motion
A distance-time graph is a good way to describe motion.
Slope is the change in the vertical axis value divided by the change in the horizontal axis value.
The slope on a distance-time graph is speed
The steeper the slope the faster the speed

11. Graphing Motion

12. This graph shows several stages of motion:
Stage 1: 100 m in 10 s
Stage 2: 50 m in 10 s
Stage 3: 150 m in 20 s
Calculate the speed as indicated by each of the colors.
Calculate the average speed.
What is the total distance?
What is the displacement?

13. Velocity Description of both speed and direction of motion
Velocity is a vector
*** A vector is a number that has magnitude and direction
A change in velocity can be the result of a change in speed, a change in direction, or both

14. Combining Velocities
Sometimes the motion of an object involves more than one velocity. If a boat is moving on a flowing river, the velocity of the river relative to the riverbank and the velocity of the boat relative to the river combine. They yield the velocity of the boat relative to the riverbank.

15. Combining Velocities
The velocity of the boat relative to the riverbank is a combination of the relative velocities of the boat and the river.
How fast is the boat travelling?

16. Combining Velocities
The velocity of the boat relative to the riverbank is a combination of the relative velocities of the boat and the river.

17. Combining Velocities Pythagorean Equation a2 + b2 = c2
The velocity of the boat relative to the riverbank is a combination of the relative velocities of the boat and the river.
How fast is the boat travelling?
Pythagorean Equation
a2 + b2 = c2