# Homework Help: Two Rpm problems

1. Jun 24, 2012

### sybozo

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

Q1) If 4,180rpm is 38% of the max rpm speed what is the max rpm speed?

Q2)Determine the number of revolutions a gear completes in 30 seconds when
the gear turns at 100 revolutions per min

2. The attempt at a solution

Q1) Alright for this part, I was pretty confuse when they asked for the max rpm speed and the given percentage. Do I have to convert the percentage to a decimal and then convert it to rads? What do they also mean by the maxrpm speed?
If I'm not mistaken, rpm is a measure of frequency right? Does that mean f=4,180rpm? In other words do I just put it in the frequency formula or should I divide it by 2∏ then put it in the frequency formula? ω=2∏f But then again it can't be ω because they're asking for speed not velocity. I could use f=1/T but they didn't give me the time. ARGH! I'm so confused!

Q2)Alright 1 revolution is equal to 60s or 2∏ right? (correct me if I'm wrong). So by using this formula, f=1/T making T=30s and well now I'm stuck

Note:Q1 and Q2 are different problems/questions

2. Jun 24, 2012

### Xisune

1) if 4180 = 38%, what is equal to 100%?

2) T is not 30s, T is the time it takes for the gear to complete 1 rev.

3. Jun 24, 2012

### sybozo

4180 = 38%
110 = 1%
11000 = 100%?

Would that be correct?

Alright so 1 rev is = 2∏ right? So, well, not sure what to do after that. I'm completely lost. Sorry about that

Does the 2∏ have to be divided by 100 or something?