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.