# Experiencing Linear and Angular Velocity

Linear and angular velocity can be one of the trickier units for high school math students.  The formulas and computations themselves aren’t all that imposing, mostly just some quick multiplications and divisions, but the vocabulary and scenarios can be intimidating.

We encounter some new terms here and their symbols, like angular velocity (ω), arc length (s), linear velocity (v) and using angles (θ) measured in radians rather than degrees.  It’s a lot of new ideas to absorb, and the problems often require a student to assess and utilize multiple formulas.  An activity which I wrote a few years ago has been taken over and perfected by a colleague.  “Trig whips” allows students to experience and communicate linear and angular velocity, and provides a great excuse to get outside and move around.

TRIG WHIPS

This activity has a simple premise.  In groups of 4, students stand shoulder to shoulder.  One student shoulder acts as the center, and the group works together as a radius, walking in a circle.  Each group records:

• Individual student distance from the center
• Time required to complete 3 revolutions
• Angular displacement

A worksheet for this activity allows students to keep track of their data.  Encourage students to switch positions and experience the effect of being the outside point.

My colleague reports that one class was able to complete the activity with a “record” 11 students.  Not only did the outside student need to run hard to keep up with the group, but the inside students worked together to slow the middle.

If we had a group of 20 students, how fast would the outside student need to “walk”?

UPDATE: More kids, a longer conga line, more chaos, more fun!

Human Chain from Bob Lochel on Vimeo.

### 9 responses to “Experiencing Linear and Angular Velocity”

1. Hello! This is really interesting. I am just beginning angular and linear velocity with my Honors Trig students tomorrow and am going to try to use it at the end of the section. About how long would you say is needed for this lesson? I know it says to have students switch rolls to see what the outside member’s experience was like. 1 or 2 days?

Thanks! – Meghan

• We have block scheduling here. But if you start with instructions inside, then venture out to collect data, it takes about 30-40 minutes. Then in-class follow-up to discuss what happened.

• Thank you. I just spoke with another Honors Trig teacher on my way out of school and we are both going to try it out! Thanks again!

2. Josie

Thanks for sharing this excellent activity.

3. John

I teach honors trig as well (second year) and am going to try this as an activity.

• Let me know how it goes. We have a lot of fun with it here and the discussions make sense.

4. Laurie Stuchlik

I’d love to see the worksheet you created. The link ins’t working. Thanks!