Question about units for arcsecond

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Homework Help Overview

The original poster is working on a problem related to determining the diameter of an object in the sky, specifically focusing on the concept of arcseconds and how to handle angular measurements in calculations.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to convert angular measurements from degrees to a usable form for their calculations, questioning how to handle the units involved, particularly in relation to the tangent function.

Discussion Status

Some participants provide clarification regarding the nature of the tangent function, noting that it is a dimensionless quantity. The discussion includes an exploration of the implications of this property for the original poster's calculations. There is an indication that the original poster has reached some understanding, but no explicit consensus is stated.

Contextual Notes

The original poster mentions needing to find the radius to determine the time it takes for an explosion to reach 1 arcsecond, suggesting specific constraints related to the problem's context.

leonne
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Homework Statement


I need to find the diameter of an object in the sky, which i did, but not sure about the arc second.
I convert it into degrees wondering how i would remove the degrees.


Homework Equations


d=2Dtan(a/2)


The Attempt at a Solution


where D is distance a is angular d is diameter and so i got like 7.47e17cm degrees do I just ignore the degrees? or I need to do something else to remove it? need the radus so i can find the time it takes the explosion to reach 1 arc sec
thanks
 
Physics news on Phys.org
The tan of an angle is a pure number without units.
 
yeah just figured it out thanks
 
gneill said:
The tan of an angle is a pure number without units.

Could you also say that the units of tan() are Length/Length = 1?
 
berkeman said:
Could you also say that the units of tan() are Length/Length = 1?

You could. Actually, it can be the ratio of any like sets of units, such as N/N, or (m/s)/(m/s), and so on.
 

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