Describing the speed of a hiker isn't as easy as describing constant speed along a straight line. A hiker may travel slowly along rocky areas but then travel quickly when going downhill. Sometimes it is useful to know how fast something moves for an entire trip. Average speed, is the total distance traveled, d, divided by the time, t, it takes to travel that distance. This can be written as an equation:
During the time an object is moving, its speed may change, but this equation tells you the average speed over the entire trip.
Calculating Average Speed
While traveling on vacation, you measure the times and distances traveled. You travel 35 kilometers in 0.4 hour, followed by 53 kilometers in 0.6 hour. What is your average speed?
Read and Understand
What information are you given?
Plan and Solve
What unknown are you trying to calculate?
What formula contains the given quantities and the unknown?
Replace each variable with its known value.
Look Back and Check
Is your answer reasonable?
Yes, 88 km/h is a typical highway speed.
A person jogs 4.0 kilometers in 32 minutes, then 2.0 kilometers in 22 minutes, and finally 1.0 kilometer in 16 minutes. What is the jogger's average speed in kilometers per minute?
A train travels 190 kilometers in 3.0 hours, and then 120 kilometers in 2.0 hours. What is its average speed?