# Determing average speed when given a circumference and flahses/min of a strobe light

1. Sep 23, 2009

### sportzmaniac

1. The problem statement, all variables and given/known data

I need to determine the average speed of a dot on a spinning motor and also the time it takes for teh dot to make on revolution. Using a strobe light I determined I needed to do 3959.2 flashes/min in order to make the dot stay in place. The dot is 6.9 cm away from the center of the motor However, I do not know how to use this in order to calculate time and I am stuck

2. Relevant equations

average speed = distance traveled (cm)/ time sec

3. The attempt at a solution

Using the 6.90 cm, i determined the circumference is 43.4 cm, and I need to use this in calculating the speed someone. However, I do not know how to use this info and the flashes/min to find either the average speed in cm/sec or the time it takes for one revolution. I need help asap please!

2. Sep 23, 2009

### kuruman

Re: Determing average speed when given a circumference and flahses/min of a strobe li

The time between flashes is the time for one revolution. Say you have 2 flashes/min then the time between flashes is 1/2 minute. Say you have 4 flashes/min, then the time between flashes is 1/4 min. Get it?

3. Sep 23, 2009

### sportzmaniac

Re: Determing average speed when given a circumference and flahses/min of a strobe li

I believe so, thank you