How can I solve this automobile physics problem involving a helium balloon?

  • Thread starter Hellsing834
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In summary, the conversation is about a question that involves an automobile traveling at a constant speed on a curved road with a child holding a helium-filled balloon in the car. The question asks for the magnitude and direction of the string angle as measured from the vertical. The person asking for help mentions using angular velocity and free body diagrams, but is unsure of how to start because the mass of the balloon is unknown. Another person suggests figuring out the minimum angle of the road if it was frictionless as a starting point. The expert then asks the person what data they have and what they think they need to solve the problem. Lastly, they ask which mass the person believes is needed.
  • #1
Hellsing834
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Hey guys, I needed help with this question:

An automobile traveling at 90 km/hr rounds a long sweeping curve of radius 250m. The air conditioner is on and the windows are rolled up so that the air within the car moves essentially as a rigid body. A child in the back seat is holding onto the string of a helium-filled balloon. On a straight road the string is vertical, but in the curve its not. Determine the magnitude and direction of the string angle as measured from the vertical.

I have no ideas on how to start, I know i have to use angular velocity/free body digrams, but the thing is, this is the only info that is given, nothing else. Could you please give some hints on how I can start this problem?

This is what I have done so far, although I can't really go ahead because the mass is unknown :(

[PLAIN]http://img806.imageshack.us/img806/8880/photobd.jpg

Thank you!
 
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  • #2
I actually had a similar problem in my first year mechanics course.
I can't recall the intimate details, but you have to figure out the minimum angle that the road has to be banked so that the car can take it at 90 km/h if the road was frictionless.
That will be the angle the balloon will be at if the air in the car is considered a rigid body.
 
  • #3
Well, let's start with seeing if you have everything you need to solve this. Take the data given and plug it into your formulas you have.

What do you have and what do you think you need?

Edit: Which mass do you think you need?
 

1. What is the difference between a fluid and a solid?

A fluid is a substance that can flow and take the shape of its container, while a solid maintains its shape and volume. This is because the molecules in a fluid are able to move freely, while those in a solid are tightly packed together.

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The pressure of a fluid can be calculated using the formula P = F/A, where P is pressure, F is force, and A is the area over which the force is applied. This means that the pressure of a fluid increases as the force applied to it increases, or as the area over which the force is applied decreases.

3. What is the difference between incompressible and compressible fluids?

Incompressible fluids are those that cannot be compressed, meaning their volume does not change when pressure is applied. Examples include liquids like water. Compressible fluids, on the other hand, can be compressed, meaning their volume can change when pressure is applied. Examples include gases like air.

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Bernoulli's principle states that as the speed of a fluid increases, its pressure decreases. This means that in a fluid flowing through a constriction, the velocity of the fluid increases, leading to a decrease in pressure. This principle is often used to explain the lift of an airplane wing.

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Viscosity is a measure of a fluid's resistance to flow. A high viscosity fluid, like honey, has a higher resistance to flow than a low viscosity fluid, like water. This means that high viscosity fluids flow more slowly than low viscosity fluids. In addition, viscosity also affects the laminar or turbulent flow of a fluid, with high viscosity fluids tending towards laminar flow and low viscosity fluids tending towards turbulent flow.

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