Speed, Velocity and Acceleration Speed, velocity and acceleration describe how an objects position and motion change through time. Rates measure change in something over a length of time.

What is speed? Speed - A measure of the distance an object travels per unit of time.

Increasing an object’s speed By increasing the distance the object travels in the same time. Or By decreasing the time it takes for an object to travel the same distance.

Calculating Speed S= d t Distance meter m kilometer km Time seconds s Speed (S) = distance object travels time it takes to travel distance S= d t Measuring Unit Abbreviation Distance meter m kilometer km Time seconds s hours hr

Calculating Speed If you know any two of the variables, you can calculate the missing variable.

Directions STEP 1 STEP 2 STEP 3 STEP 4 Write the correct formula Plug in the information that you are given STEP 2 STEP 3 Solve the answer STEP 4 Add your units

PRACTICE S= 4 meters/second Calculate the speed of a car going 80 meters in 20 seconds. S= D T S=80 meters 20 seconds S= 4 meters/second

PRACTICE S=2.5 meters/second A girl runs 25 meters in 10 seconds. What is her speed? S= D T S=25 meters 10 seconds S=2.5 meters/second

Constant Speed The rate of change of position in which the same distance is traveled each second.

Average speed = total distance total time traveled S= td tt

Solve the average speed: Melissa shot a model rocket 360 m into the air. It took the rocket 4s to fly that far. What was the average speed of the rocket? S= td tt S=360 meter 4 seconds S=90 meters/second

If Jessica ran 5 meters the first second, 8 meters the next second, and 8 meters the third second to her house. What was her average speed? S= td tt S=5 meters + 8 meters + 8 meters = 21 m 3 seconds 3 s S=7 meters/second

Speed at a specific instant in time. Instantaneous Speed Speed at a specific instant in time. When driving in a car you often change speed. What object in the car tells you your instantaneous speed? Speedometer