Speed

Review of Motion Motion is the change of position over time. Position is an object’s location Reference Point is the location to which another location is compared

What is Speed? Speed is the measure of how fast something moves or the distance it moves in a given amount of time.

How do we calculate speed? Speed is the rate of distance over a period of time. Therefore, we can calculate speed using the formula: S= Speed D= Distance T= Time

Sample Problem #1 Maria walked 2 km in half an hour. What was her speed during her walk?

Sample Problem #1 Formula- Substitute- Speed = ? We will use variable S Distance= 2 km Time= 0.5 hour Solve- S = 2km/ 0.5 hour Answer- S= 4 km/hr

Sample Problem #2 A wheelchair racer completes a 100- meter course in 20 seconds. What is his speed?

Sample Problem #2 Formula- Substitute- Speed = ? We will use variable S Distance= 100 meters Time= 20 seconds Solve- S = 100 m/20 sec Answer- S = 5 m/sec

Sample Problem #3 A cheetah runs a speed of 30 meters per second. How long does the cheetah take to run 90 meters?

Sample Problem #3 Formula- Substitute- Speed = 30 meters per second Distance= 90 meters Time= ? We will use variable T Solve- 30 = 90/T 30T=90 T=90/30 Answer- T= 3 Seconds

What is average speed? Speed is not constant. For example, if you are running… Sometimes you will speed up Sometimes you will slow down Average Speed = Total Distance Total Time

Distance vs. Time Graph What does this graph tell us about the motion of the helicopter? Did not travel at a constant speed Faster between 4-7 seconds Slow down between 2-4 seconds. Helicopter Motion