Speed describes how fast an object is moving. Velocity refers to the speed and the direction of motion. Speed is described in units of distance and time. For example, the speed of a car is often described in miles per hour. Miles is the unit of distance, hour is the unit of time. Speed can also be measured in kilometers per hour, feet per second and in almost any combination of distance and time. Speed is calculated by dividing the distance traveled by the time it took to travel this distance.

Since speeding objects seldom maintain one constant speed, speed is usually measured as an average speed. Average speed is calculated by dividing the total distance traveled by the total time it took to travel this distance. If, for example, a person drove 500 miles in 10 hours, their average speed would have been 500/10=50 miles per hour (mph). If an airplane traveled 500 miles in one hour, what was the average speed of the airplane? (500 mph)

Cruise control on a car allows you to drive at a constant speed. If you set your cruise control on 65 MPH, how far would you go in three hours? How far in ten hours? (195 miles), (650 miles)

In common speech, the word accelerating means to speed up. However, in science, the word acceleration refers to any change in speed or direction. Since the word velocity refers to speed and direction, acceleration is any change in velocity. So acceleration describes how fast the velocity is changing.

By calculating the amount of fuel consumed per distance traveled, you can get a rating of fuel efficiency for a motor vehicle. This is usually expressed as miles per gallon (mpg). The gallon refers to a gallon of gasoline. If a car requires 10 gallons of gas to travel 100 miles, it is getting 10 miles per gallon. 10 gallons times 10 miles per gallon equals 100 miles. Miles per gallon is calculated by dividing the total number of miles traveled by the total number of gallons of gasoline required to travel this distance. If on 10 gallons of gasoline a car can travel 500 miles, how many miles per gallon is the car giving? 500/10=50 miles per gallon (MPG).

Problems:

1. If a motorist fills up their car's gasoline tank with gasoline and drives 450 miles, and it requires 10 gallons to fill the tank again, how many miles per gallon is this car getting?

2. If a runner runs ten miles in two hours, what is the runner's average speed?

3. If a car gets 45 miles per gallon and travels a distance requiring 5 gallons of gasoline, how far did the car travel?

4. If a car gets 25 miles per gallon, how many gallons will it require to travel 750 miles?

5. If a car gets 30 miles per gallon, and gasoline costs $1.03 per gallon, how much will it cost to travel 390 miles?

6. If an airplane travels at an average speed of 550 miles per hour, how long will it take for the airplane to travel 2,000 miles?

7. A biker travels a distance of 25 miles in 10 minutes. What is the biker's average speed? Express your answer in miles per hour.

8. If a rocket travels an average speed of 200 feet per second,

how many miles per hour is the rocket traveling?

9. If a car gets 25 miles per gallon on regular gasoline and 30 miles per gallon on premium gasoline, and regular gasoline cost $1.02 per gallon and premium costs $1.19, which fuel would be most economical for this car to use?

10. How long will it take for a motorist to travel a distance of 800 miles, if they maintain an average speed of 60 miles per hour?