Find the value of aerodynamic constant C for this dimpled sphere.

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Homework Help Overview

The discussion revolves around determining the aerodynamic constant C for a dimpled sphere, specifically a golf ball, which is experiencing terminal velocity during free fall. The problem involves concepts from fluid dynamics and motion, particularly focusing on the forces acting on the ball as it falls.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to apply a formula related to centripetal force but questions its applicability to the context of terminal velocity. Other participants suggest using the correct formula for terminal speed and raise questions about unit consistency, particularly regarding the density of the fluid and the units for velocity and radius.

Discussion Status

Participants are exploring the correct formula to use for terminal velocity and discussing unit conversions necessary for consistency. There is an ongoing examination of the assumptions related to the variables involved, particularly the density of the fluid and the appropriate units for the calculations.

Contextual Notes

There is some confusion regarding the units of measurement, with discussions about converting to MKS units and the implications of using different unit systems. The original poster's understanding of the aerodynamic constant C and its role in the equation is also under scrutiny.

Sneakatone
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A falling golf ball (mass 45 g, radius 20.0mm) reaches high terminal speed of 42 m/s. what is the value of the aerodynamic constant C for this dimpled sphere?

I tried using mv^2/r -> (0.45 kg)*(42 m/s)/0.2m=94.5 but Its not correct. I don't understand what they mean by constant C.
 
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Well, the golf ball is undergoing linear motion. Your formula is for the centripetal force on an object in circular motion. What you need is a formula for terminal speed of an object which is falling.
 
V=sqrt(2mg/pAC)
 
if this is the right equation should the units of v=km/h and r=m?
in other words what should the units be?
 
Sneakatone said:
if this is the right equation should the units of v=km/h and r=m?
in other words what should the units be?
Anything you like as long as you are consistent. Put everything into MKS units and you should be safe.
 
would you recommend I convert to km since p is km?
 
Last edited:
Sneakatone said:
would you recommend I convert to km since p is km?

Isn't p (rho) the density? That would be kg/m3 in MKS.
 

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