Students will measure distance traveled and time traveled to determine velocity in a similar manner to speed determination in the activity: Using an Active Model to Measure Speed . However, velocity differs from speed in that it is a vector quantity and includes a direction.
This activity should follow the above-mentioned activity, ideally within a day or two so that content from the speed activity is still fresh in the students’ minds. It should also immediately follow instruction on velocity.
Speed: a measurement of how fast something moves, the rate of motion
Formula for speed: Speed = Distance / Time
Velocity: the speed of an object in a particular direction
Vector: a quantity that has both size and direction
Stopwatch (iPad or other apple devices have a nice stopwatch feature and this allows students to practice its use.)
If an Apple product is not available, use a different inexpensive talking timer.
The instructor will simply need to gather materials for this activity and willing participants.
A trundle wheel, a stopwatch, and the means to record data are all that are necessary for this activity.
Have students prepare to complete a written warm-up. Ask students what information was necessary to determine speed. Have students write down what was measured and the formula used. In this manner all students have the opportunity to respond. Discuss only after all students are done. Tell students that today we will measure not only speed, but also velocity. Ask students to remember the prior lesson: What else will be part of this measurement? Discuss: Velocity is determined by dividing distance by time (like speed), but includes direction as well.
Before beginning this activity, talk about which directions you will be walking. Choose at least two different directions and measure distance and time in each direction. Discuss cardinal directions if necessary.
Distance and time will be measured in a manner similar to the measurement of speed, however direction will be included in the measurement of velocity.
Distance measurement using the trundle wheel:
Measure distance traveled in a known direction. If necessary, a compass may be utilized. One student should be responsible for taking this measurement and counting clicks on the trundle wheel.
Time measurement using a stopwatch:
Have two members of the class measure time using a stopwatch. The stopwatch feature on the iPad or other i-device are particularly accessible for students with visual impairments. This allows students to check each others’ measurements.
Calculation of speed
After returning to the room, calculate speed in m/sec using the formula Speed = distance/time. Convert from minutes to seconds as necessary.
Have students work in groups to determine speed for each trial or have them work independently if time and math skills allow.
Closure: Calculation of Velocity
Ask students: “What do we need to do with these measurements now to determine velocity?”
Discuss. Students will take each of the measurements and convert from speed to velocity by adding the direction. Example: .75 m/sec= speed .75 m/sec east = velocity
Review the terms speed, velocity, and vector from the vocabulary section above.
Middle School – Forces and Interactions
PS2.A: Forces and Motion All positions of objects and the directions of forces and motions must be described in an arbitrarily chosen reference frame and arbitrarily chosen units of size. In order to share information with other people, these choices must also be shared. (MS-PS2-2)