# Tag - Constant Velocity

A truck is traveling 60mph (Constant Velocity), a baseball shoots out of the back at 60mph. Do you really expect the ball to drop straight down?

The following video from a Japanese TV show should be a good laugh for anyone teaching science, regardless of what area you focus on. This video uses a vehicle traveling at high speeds, combined with a radar gun and a mounted baseball pitching machine. Using creativity and access to a driving test track, they drive the vehicle 100km/Hr in one direction while hurling a baseball 100km/Hr in the opposite direction. From the frame of reference (the earth), the two velocity’s vectors are represented with opposite numerical signs, one being positive and the other negative. The net result when adding these vectors is zero velocity relative to the earth and the ball drops straight down. When the slow motion video is shown, it provides a stunning example of net velocity and vector addition and can lead to a discussion of Galilean relativity.

Please Note: forward past the first 26 seconds, since it is an introduction to the show in Japanese.

Thank you to Buzz Putnam of Whitesboro High School for sharing this video! We certainly don’t recommend trying this one at home, or at school, but you can show them this video, and with the mute setting and your commentary, this could be a fun way to introduce this concept to your students in an engaging and educational way.

This just in: In response to the Coolstuff newsletter email, Stanley Micklavzina of the University of Oregon shares this vector addition related video from the popular Mythbusters television series. Velocity and vectors are often among the first topics covered in the Physics classroom and a key concept to grasp early on for most other science disciplines. It is also one of the more difficult subjects for a student to understand. The good news is that it can be a fun subject to demonstrate. Active demonstrations can help lead your students to a much deeper understanding of the concepts they need to grasp for whatever subject you teach. Of course, an even better way to introduce students to this concept is to show them in person. While we wouldn’t recommend trying the activities in the video, here are some popular items from Arbor Scientific that could be used to demonstrate vector addition in other ways:

Ballistics Car
A classic demonstration that still amazes students. Compare the speed of the cart to the horizontal speed of the ball. Show the independence of the vertical and horizontal motion of the ball.

## Ballistics Car

In Stock SKU: P3-3527
\$65.00

Demo A Day for Physics
384 pages spiral bound. Demo A Day for Physics is just the thing for a complete reference guide to demonstrations and experiments that will add to the excitement in your classroom.

## Demo A Day for Physics

In Stock SKU: P8-0650
\$45.00

Check that speed just like the pros! With the Velocity Radar Gun accurate velocity readings are now as easy as “point and shoot”.

In Stock SKU: P4-2130
\$139.00

## Measuring Constant Velocity

Measuring Constant Velocity

A moving object experiences a change in its position in a certain time. For constant velocity, the change in position over each equivalent time period is constant. Students will graph the position vs. time of a moving car. The graph will be a straight line whose slope is the car’s velocity.

Required Equipment
Constant Velocity Car, Measuring Tape, Stopwatch, Chalk, Graph paper

Acknowledgements: Thank you to Cary Busby for her work in developing this lab. Cary is a former high school physics teacher and has presented physics related workshops at NSTA conferences and State science conferences around the country.

## Constant Velocity Car (Carts)

In Stock SKU: 44-1090
\$8.75

## Analyzing Motion

“When I pull out the constant velocity cars, I usually hear a chorus of, ‘All right!’ from the class. That’s what I think, too, because these powerful miniature dune buggies are so effective at helping my students really grasp what constant motion is and how to graph it. They get immediate kinesthetic and visual feedback, and I get the satisfaction of making a solid lesson super fun.” – Mark Davids

Constant Velocity Demonstration

You’ll need paper strips, markers, plus a constant velocity car and a metronome that beeps. Have students lay out paper strips to form a “road” for the car. Explain that they’ll start the car, then mark its position at each beep of the metronome.

Start the metronome and have students start their cars. They will clearly see that the marks are equally spaced. Have them predict how the marks would fall with a faster car, and then have them check by increasing the speed of the car.

Have students graph the position vs. time results and they’ll see nice, smooth curves that suggest the slope of the graph represents a constant velocity. They can also run the cars in the opposite direction — and discover that negative velocity produces a negative slope when graphed.

Mark Davids is a Presidential Award winner and recipient of the Excellence in Pre-College Physics Teaching Award, Mark has been teaching students and teachers for more than 37 years. He has written curricula, content standards and served as a grant reviewer, along with presenting at local, state and national conferences.

Required Equipment

Paper strips, Markers, a Constant Velocity Car and a Metronome.
Recommended quantity per lab group: 1

## Constant Velocity Car (Carts)

In Stock SKU: 44-1090
\$8.75