Speed Notes

SPEED

How is motion measured?

How do you know how fast or

slow something is?

Speed

In general, speed measures the distance
traveled in a given amount of time, however speed is not constant.


- For example, when you are running a race you may start out slower to pace yourself, but as you near the finish line you speed up.

Match

Match the following

• Speed

• Motion

• Distance

• Position

Distance traveled over time

Change in position over time

The length traveled between 2 positions

Location of an object at a given time

• Distance traveled over time

• Change in position over time

• The length traveled between 2 positions

• Location of an object at a given time

Speed

The moment-to-moment speed is harder to measure, though may be needed for some problems.

However, if you only need an estimate of the speed throughout the entire race you can use a different calculation. These ways two of measuring speed allows physicists to get the information that they need.

Multiple Choice

True or False. There are two different calculations for instantaneous speed and average speed.

• True

• False

Speed

Average speed will measure the overall speed of an object during the entire course of a trip. This is
calculated by taking the total distance traveled divided by the total time elapsed.

Speed

Instantaneous speed will measure the speed of an object at a specific moment in time.

​Jack's speed 0.3min/mile

​

Multiple Choice

What is the formula for average speed?

• S= d/t

• S= t/d

• S= (3.14)d

• S=bh

Speed
Steps for calculating average speed from a word problem.

1. Read the word problem
2. Identify the total distance traveled with the unit

3. Identify the total time with the unit
4. Plug values into the equation
5. Divide distance by time
6. Write the answer with the correct unit

Multiple Choice

What is the first step for fining speed in a word problem?

• Find the total distance

• Find the total time

• Read the problem

• Calculate speed

Practice Problem

Becky and her family took a trip to the Grand Canyon for
spring break. They traveled a distance of 1,950 miles. It
took them 25 hours to reach the Grand Canyon. Calculate
the average speed.

Multiple Choice

What is the average speed Becky and her family traveled?

• 0. 0.013 mph

• 78 mph

• 0.012 mph

• 76 mph

Practice Problem

Johnny flew from New York to Los Angeles to visit family.
The trip took a total of 5 hours and covered
2,450 miles.

Multiple Choice

What is the average speed the plane flew?

• 490 mph

• 500 mph

• 49 mph

• 50 mph

Practice Problem

Sandra went on a road trip with her family. The entire trip
took 7 hours, however they had to make a few
stops along the way. In the first 2 hours the family traveled a
100 miles before they stopped at a rest stop.
The family traveled 160 miles in the next 2 hours. After they
stopped for food they traveled the final 230
miles to reach their destination.

Multiple Choice

What is the average speed Sandra and her family traveled?

• 70 mph

• 75 mph

• 60 mph

• 72 mph