Yes, I understand now. Thank you for explaining it to me.

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In summary: The 2 was just a simple example to try to get you to understand where the formulas are coming from. Here, I'll spell it out: if p is period in seconds, then 60/p is revolutions per minute. 1/p is revolutions per second. Can you understand why?
  • #1
vanitymdl
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A electric model train travels at 31.7 cm/s around a circular track of radius 1.73 m. How many revolutions does it perform per second, i.e, what is the motion\'s frequency?
______ Rev / s

Find the train\'s period of revolution.
______ s

This is how I worked out the problem:
v^2/r = rw^2
.317^2/1.73 = 1.73w^2
.317^2/1.73^2 = w^2
w = 0.18323699421 radians per second.
there are 2 pi radians, so it takes 2pi radians / .1832 radians/second = seconds

34.3 seconds
1.75 revolutions per second (60/34.3)

I'm getting that 1.75 rev/s is wrong and I don't know why or how
 
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  • #2
vanitymdl said:
A electric model train travels at 31.7 cm/s around a circular track of radius 1.73 m. How many revolutions does it perform per second, i.e, what is the motion\'s frequency?
______ Rev / s

Find the train\'s period of revolution.
______ s

This is how I worked out the problem:
v^2/r = rw^2
.317^2/1.73 = 1.73w^2
.317^2/1.73^2 = w^2
w = 0.18323699421 radians per second.
there are 2 pi radians, so it takes 2pi radians / .1832 radians/second = seconds

34.3 seconds
1.75 revolutions per second (60/34.3)

I'm getting that 1.75 rev/s is wrong and I don't know why or how

I would just use v=rw. It's a more basic formula. But it's going to give the same thing. You've got 34.3 seconds for the period ok. And 60/34.3 would be ok if you wanted revolution/minute because there are 60 seconds in a minute. But that's not what they are asking for. Can you fix it?
 
  • #3
But I thought 60/34.3 would give me the seconds? So what you're saying is that I have to convert 60/34.3 re/min to rev/sec? Isn't that what 34.3 is, it's seconds
 
  • #4
vanitymdl said:
But I thought 60/34.3 would give me the seconds? So what you're saying is that I have to convert 60/34.3 re/min to rev/sec? Isn't that what 34.3 is, it's seconds

If a revolution takes 2 seconds, how many revolutions per second? There is really no 60 needed.
 
  • #5
Okay so if it take 2 seconds per revolution. I would take my seconds which is 34.3 and multiply it by 2?
 
  • #6
vanitymdl said:
Okay so if it take 2 seconds per revolution. I would take my seconds which is 34.3 and multiply it by 2?

Noo. If it takes 2 seconds to make a revolution, then in 1 second it will make 1/2 revolution. So that's 1/2 revolution per second. Not 60/2. Just think about it. This is a different question.
 
  • #7
Okay well I'm still getting it wrong but thank you anyway
 
  • #8
vanitymdl said:
Okay well I'm still getting it wrong but thank you anyway

You're welcome. But think about this. Where did the 60 in your problem even come from? I think you are just plugging into formulas without thinking about what they mean.
 
  • #9
What I understood is I get 34.3/2 and get 17.5 but that's still the wrong answer
 
  • #10
vanitymdl said:
What I understood is I get 34.3/2 and get 17.5 but that's still the wrong answer

The 2 was just a simple example to try to get you to understand where the formulas are coming from. Here, I'll spell it out: if p is period in seconds, then 60/p is revolutions per minute. 1/p is revolutions per second. Can you understand why?
 

1. What is motion's frequency?

Motion's frequency refers to the number of times an object completes a full cycle of motion in a given time period. It is often measured in hertz (Hz) or cycles per second.

2. How is motion's frequency related to its speed?

The frequency of an object's motion is directly proportional to its speed. This means that as the frequency increases, the speed of the object also increases.

3. Can motion's frequency change?

Yes, the frequency of motion can change. It can be affected by factors such as changes in speed or direction, as well as external forces such as friction or gravity.

4. What is the difference between motion's frequency and its period?

Motion's frequency and period are inversely related. While frequency measures the number of cycles in a given time period, period measures the time it takes for one full cycle of motion. They are related by the equation: frequency = 1/period.

5. How is motion's frequency measured?

Motion's frequency can be measured using a stopwatch or timer to track the number of cycles completed in a certain amount of time. It can also be measured using specialized equipment such as an oscilloscope or motion sensor.

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