1. Speed and Acceleration
Measuring motion

2. Calculating Speed S = d/t
Speed (S) = distance traveled (d) / the amount of time it took (t).
S = d/t

3. Units for speed
Depends, but will always be a distance unit / a time unit
Ex. Cars: mi./h
Jets: km/h
Snails: cm/s
Falling objects: m/s

4. Measuring Distance Meter – international unit for measuring distance.
1 mm
= 50 m

5. Calculating speed S = d/t
If I travel 100 kilometer in one hour then I have a speed of…
100 km/h
If I travel 1 meter in 1 second then I have a speed of….
1 m/s

6. Speed
Average Speed
Sometimes it is useful to know how fast something moves for an entire trip, even though its speed may change during the trip.
Average speed, is the total distance traveled, d, divided by the time, t, it takes to travel that distance.
s = d/t

7. Example: A car’s speedometer Speed Instantaneous Speed
Sometimes you need to know how fast you are going at a particular moment.
Instantaneous speed, s, is the rate at which an object is moving at a given moment in time.
The speedometer in a car measures the car’s instantaneous speed.
Example:
A car’s speedometer

8. Velocity Velocity – the SPEED and DIRECTION of an object. Example:
An airplane moving North at 500 mph
A missile moving towards you at 200 m/s

9. Given - Write out your givens
Guess Method to solve:
Given - Write out your givens
Unknown – What is the problem asking you to solve?
Equation - What equation do you use?
Substitution - Plug in the numbers
Solution - Write your answer, with correct units.
Sample Problem:
A train travels 190 kilometers in 3.0 hours, and then 120 kilometers in 2.0 hours. What is its average speed?
It is important for students to follow the five step process in solving story problems. It helps them think through it more logically. If they can do simple problems, it really sets them up for success for more complicated problems!

10. t1 d1 d2 t2 s Givens: 190 km = 120 km = 3 hr = 2 hr = Unknown =
s = total distance
total time
Equation =
s = 190 km km
3 h + 2 h
Substitution=
Walk the students through this step by step. Have them tell you what variable to use for each number.
On the answer portion: explain how the s in the m/s goes on the bottom, then how a s times a s = a second squared
s = 310 km
5 h
s = 62 km h
Solution =

11. Solve Using the GUESS Method
If you move 50 meters in 10 seconds, what is your speed?
How much time will it take for a bug to travel 5 meters across the floor if it is traveling at 1 m/s?
If you shout into the Grand Canyon, your voice travels at the speed of sound (340 m/s) to the bottom of the canyon and back, and you hear an echo. How deep is the Grand Canyon at a spot where you can hear your echo 5.2 seconds after you shout?

12. Question What is the difference between speed and velocity?
Speed is just distance/time. Velocity includes direction as well.
Speed is just distance/time. Velocity includes direction as well.