Solving Bacterial Motor Angular Speed and Time for One Revolution

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Homework Help Overview

The discussion revolves around a problem involving the angular speed and time for one revolution of a bacterial motor, which is characterized by its radius and tangential speed. The subject area includes concepts from rotational motion and angular velocity.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculation of angular speed and the time taken for one complete revolution. There are attempts to clarify the correct formula for determining the period of rotation and the relationship between angular speed and time.

Discussion Status

The discussion is active, with participants offering insights into the calculations and questioning the units involved in the answers. Some guidance has been provided regarding the conversion of units and the formula for the period of rotation, although there is no explicit consensus on the final approach.

Contextual Notes

There is mention of a discrepancy between the calculated time for one revolution and the expected answer from the homework program, indicating potential misunderstandings or missing information in the problem setup.

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Homework Statement


Some bacteria are propelled by motors that spin hair-like flagella. A typical bacterial motor turning at a constant angular velocity has a radius of 1.8x10-8m, and a tangential speed at the rim of 1.8x10-5 m/s. (a) What is the angular speed (the magnitude of the angular velocity) of this bacterial motor? (b) How long does it take the motor to make one revolution?


Homework Equations


Vt= rw
rad/s / 2pi = rev/s


The Attempt at a Solution


I got part A which is 1000rad/s. but Part B I can't get. If its supposed to be 1000/2pi = 159.15 then something is wrong. I know I'm missing something cause the answer my homework program is giving me is .0063s. So what equation should I be using?
 
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In part b, you are supposed to calculate how long it takes to make one revolution. What is the formula for calculating the period?
 
If you write the units of your answer for B, you will see that it is rev/s, not s/rev which is what the question is asking for. It should be pretty easy to convert that one.
 
SteamKing said:
In part b, you are supposed to calculate how long it takes to make one revolution. What is the formula for calculating the period?

T=(2pi(r))/V ?
 
If a shaft rotates at 10 revolutions per second, how long does each revolution take?
 
.1 seconds.

OH! I think I got it thanks.

So I take the 1000/2pi to get the 159.xxx and then do 1/159 = .0062893 and round to get .0063. thanks!
 
Last edited:

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