SPEED MEASURES HOW FAST POSITION CHANGES SPEED Speed

SPEED MEASURES HOW FAST POSITION CHANGES

SPEED Speed is how fast positions change with time Speed = 00: 00 distance time 00: 02 distance

SPEED A measure of how fast something moves through a particular distance over a definite time period.

YOU TRY Suppose a race is 50 m and it takes an athlete 15 seconds to run it. Is that enough information to calculate the runner’s speed? � Think-pair-share � YES, (2 minutes) the formula for speed = distance time

AVERAGE SPEED Imagine taking a road trip with your friends or family. When you travel in your car do you stay at a constant speed? THIS IS YOUR AVERAGE SPEED

AVERAGE SPEED Usually objects do not travel at a constant speed. Do you run at a constant pace when you run for a mile in PE class? Think about when you are riding somewhere and you hit traffic. It is more useful to calculate an objects average speed using the following equation:

AVERAGE SPEED EXAMPLE Think about when you meet your friends at the movies You say “I’ll meet you there in 20 minutes. ” Are you traveling at a constant rate for 20 minutes? No, instead we average the speed. We went 5 miles in 20 minutes so what is my average speed to meet your friends at the movies? . 25 miles/minute

AVERAGE VS. INSTANTANEOUS SPEED During a typical trip to school, your car will undergo a series of changes in its speed. If you were to inspect the speedometer readings at regular intervals, you would notice that it changes often The speedometer of a car reveals information about the instantaneous speed of your car. Instantaneous speed- speed at a particular instant in time. (NOT AVERAGE SPEED)

AVERAGE VS. INSTANTANEOUS SPEED Average speed � Measure of distance traveled in a given period of time. � Ratio: distance per time

AVERAGE VS. INSTANTANEOUS SPEED Suppose that during your trip to school you traveled a distance of 5 miles and the trip lasted 0. 2 hours (12 minutes) What is your average speed? � Average speed= 5 miles/0. 2 hours= 25 mph What is your instantaneous speed? � Speed at the particular moment you looked at the speedometer

FORMULAS Speed= Distance/time How would average speed differ? Average speed = Total Distance/Total Time

PROBLEM 1: If your great aunt Betty traveled 2500 miles from LA to New York in 4 hours, what is the average speed of the airplane?

PROBLEM 2: It takes you 9 minutes to run 1 mile. What is your average speed in miles per minute? In miles per hour? . 11 miles/minute 6. 67 miles/hour