# Homework Help: Spark tape?

1. Sep 26, 2007

### Nick A

Well I used a spark timer and got a spark tape, but forgot how to use the spark tape to calculate time and velocity.
I think its something like the number of dots/60 to get time and v=d/t to get velocity
Am I right?

2. Sep 26, 2007

### Staff: Mentor

What's a spark tape?

Sounds like you have the right idea, though.

3. Sep 26, 2007

### Nick A

Spark Tape is the tape u insert into the spark timer

4. Sep 26, 2007

### mgb_phys

I'm guessing it's like the ticker tape counters in school dynamics experiments.

You have a length of lightweight paper tape which attaches to the moving object and goes through a mains fed coil which taps a bit of carbon on the paper every 1/50 or 1/60 second to give a time-displacement relation. I suppose you could use a mains spark to burn marks on the paper rather than draw them.

Nick - The marks will be either 1/60s apart in USA/Canada or 1/50s in Europe.

5. Sep 26, 2007

### Nick A

yea that was what we did, thx!

6. Sep 26, 2007

### Staff: Mentor

Thanks mgb_phys, I'd never heard of that before.

7. Sep 27, 2007

### TVP45

So, measure the distance between each spot. Make a chart. What does this represent?
What is the time between each spot? What made them? How are they related to the frequency of the power mains?
How can you manipulate (add, subtract, multiply, or divide?) those quantities to get velocity? What kind of velocity (average or instantaneous) do you think you have?
What else could you do with the velocities?