1. What is speed?

2. Watch the toy car: (pull back car) Watch the toy car: (pull back car) What did you see? What did you see? The car changed positions. The car changed positions. How does what you saw define the term SPEED? How does what you saw define the term SPEED? How fast an object is moving or changing positions. How fast an object is moving or changing positions. Speed is the rate at which distance is covered. Speed is the rate at which distance is covered. Why is speed referred to as a RATE? Why is speed referred to as a RATE? Rate is a clue that something is changing in a time period. Rate is a clue that something is changing in a time period. Heart rate Heart rate Interest rate Interest rate Dropout rate Dropout rate

3. What is a SCALAR QUANTITY? What is a SCALAR QUANTITY? A quantity in which direction is either n/a or not specified. A quantity in which direction is either n/a or not specified. temperature temperature What are the units of speed? What are the units of speed? any distance unit / any time unit any distance unit / any time unit mph mph km/h km/h cm/day cm/day What are the most common units we will use for speed? What are the most common units we will use for speed? meters per second m/s meters per second m/s kilometers per hour km/h kilometers per hour km/h

4. Examples of speeds: km/hmphm/s 20126 402511 603717 805022 1006228 1207533

5. The speed equation: The speed equation: In words: In words: speed=distance / time speed=distance / time In symbols: In symbols: s= d/t s= d/t The wheel: The wheel: Cover the unknown Cover the unknown d st

6. Let’s look at other types of speed: Let’s look at other types of speed: How can you tell a car’s speed at a given instant in time? How can you tell a car’s speed at a given instant in time? look at the speedometer look at the speedometer What is this type of speed called? What is this type of speed called? instantaneous speed instantaneous speed Example-Bus ride to school this morning Example-Bus ride to school this morning

7. In riding the bus this morning, the driver has an idea of how long it will take to cover a certain distance. The bus did not travel the same speed during the whole trip. What is the type of speed the driver is concerned with? In riding the bus this morning, the driver has an idea of how long it will take to cover a certain distance. The bus did not travel the same speed during the whole trip. What is the type of speed the driver is concerned with? AVERAGE SPEED AVERAGE SPEED What is the formula for this type of speed? What is the formula for this type of speed? average speed = total distance / total time average speed = total distance / total time s = d t /t t s = d t /t t What does the bar over the s indicate? What does the bar over the s indicate? average average

8. Watch your teacher: Watch your teacher: How is this type of speed different than what you have seen so far? How is this type of speed different than what you have seen so far? covered same distance with each step Watch the car: (battery operated car) Watch the car: (battery operated car) What would you call this type of speed? What would you call this type of speed? constant speed constant speed equal distances in equal amounts of time equal distances in equal amounts of time

9. How does the driver of an automobile ensure they are traveling at this type of speed? How does the driver of an automobile ensure they are traveling at this type of speed? Cruise control Cruise control What are the parts of a car that control speed? What are the parts of a car that control speed? gas pedal (accelerator) gas pedal (accelerator) brake pedal (decelerator) brake pedal (decelerator) NO MATTER WHAT TYPE OF SPEED WE ARE TALKING ABOUT WE ARE STILL INTERESTED IN THE CHANGE OF POSITION IN A GIVEN AMOUNT OF TIME. NO MATTER WHAT TYPE OF SPEED WE ARE TALKING ABOUT WE ARE STILL INTERESTED IN THE CHANGE OF POSITION IN A GIVEN AMOUNT OF TIME.

10. Sample Problems: Sample Problems: 1. What is the average speed of a marble that rolls 45 centimeters in 5 seconds? 1. What is the average speed of a marble that rolls 45 centimeters in 5 seconds? G d= 45cm d= 45cm t= 5s t= 5s U s =? s =? E s = d t /t t s = d t /t t

11. S s = 45cm / 5s = 9cm/s s = 45cm / 5s = 9cm/s S s = 9cm/s s = 9cm/s