Finding revolution time at surface

In summary, for a 0.90km radius cylinder, the time for one revolution can be found by using the formula ω = v/r, where ω is the angular velocity, v is the velocity, and r is the radius. After converting the radius to 900m and using the given value of 9.8 m/s^2 for acceleration due to gravity, the angular velocity is calculated to be 0.104 rad/s. This value can then be plugged into the equation rω^2 = a to find the time for one revolution.
  • #1
ross moldvoer
16
0

Homework Statement


For a 0.90km radius cylinder, find the time for one revolution if "gravity" at the surface is to be 9.8 m/s2.

Homework Equations


rω^2=a

The Attempt at a Solution


i tried solving for omega but i couldn't find a solution that i only had 1 variable in it.
 
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  • #2
ross moldvoer said:

Homework Statement


For a 0.90km radius cylinder, find the time for one revolution if "gravity" at the surface is to be 9.8 m/s2.

Homework Equations


rω^2=a

The Attempt at a Solution


i tried solving for omega but i couldn't find a solution that i only had 1 variable in it.
Which other variable do you think you have no value for?
 
  • #3
haruspex said:
Which other variable do you think you have no value for?
i don't know the velocity for solving for omega, is this what you meant?
 
  • #4
ω is a velocity: an angular velocity. How is ω related to the frequency and the period of one "cycle" (one revolution in this case)?
 
  • #5
ross moldvoer said:
i don't know the velocity for solving for omega, is this what you meant?
I don't know where you are stuck. The first step is to calculate ω - can you do that from the formula you quoted? Next, as gneill says, you can find the time of one revolution from ω. Is that part your problem?
 
  • #6
i know that ω = v/r but i do not know v. I guess i am confused about what to do in order to solve for ω.
 
  • #7
ross moldvoer said:
i know that ω = v/r but i do not know v. I guess i am confused about what to do in order to solve for ω.
In the OP you quoted the right equation to be using. That has three variables and you are given the values of two of them. Forget v for now.
 
  • #8
wow can't believe i missed that. so then 450ω^2=9.8, ω=.133
i converted .9 km to 900 m
 
Last edited:
  • #9
ross moldvoer said:
wow can't believe i missed that. so then 450ω^2=9.8, ω=.133
i converted .9 km to 900 m
Ok, but why did you halve it to 450? Either way, I don't get .133.
 
  • #10
haruspex said:
Ok, but why did you halve it to 450? Either way, I don't get .133.
the cylinder's diameter is 900m and i need the radius. 900/2=450. then i did 9.8/450=ω^2=.022, ω=.147
(i had a math error in the previous post, this is what i actually got)
 
  • #11
ross moldvoer said:
the cylinder's diameter is 900m
It says radius.
 
  • #12
haruspex said:
It says radius.
my bad

then i get .104
 
  • #13
ross moldvoer said:
my bad

then i get .104
Sounds right.
 
  • #14
so after this do i just plug it into the equation? the answer i get seems high
 
  • #15
ross moldvoer said:
so after this do i just plug it into the equation? the answer i get seems high
You know what I'm going to say, surely? Please post your working and answer.
 

What is revolution time at the surface?

Revolution time at the surface refers to the amount of time it takes for a planet or celestial body to complete one full orbit around its parent star or central body while staying at the same distance from the central body's surface.

Why is it important to calculate revolution time at the surface?

Calculating revolution time at the surface allows us to understand the orbital dynamics of a planet or celestial body. This information is crucial in predicting and understanding astronomical events, such as eclipses, and in studying the evolution of planetary systems.

How is revolution time at the surface calculated?

Revolution time at the surface is calculated using Kepler's third law of planetary motion, which states that the square of the orbital period is proportional to the cube of the semi-major axis of the orbit. This means that revolution time at the surface can be calculated by knowing the distance between the planet and its parent star, and the mass of the parent star.

Can revolution time at the surface change?

Yes, revolution time at the surface can change over time due to various factors such as gravitational interactions with other objects, tidal forces, and changes in the planet's orbit. However, these changes are usually very small and can only be observed over long periods of time.

What is the difference between revolution time at the surface and rotation time?

Revolution time at the surface refers to the time it takes for a planet to complete one orbit around its parent star, while rotation time refers to the time it takes for a planet to complete one full rotation on its axis. These two times can be different, as some planets have longer or shorter days than their years due to their rotation speeds and orbital distances.

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