# Help in calculation

1. Jan 9, 2009

### brazil2200

Please can anyone help me to resolve this problem:

a solid sphere 2.54 cm in diameter is placed in an otherwise undisturbed air stream, which approaches at a velocity of 30.48 m\s, a pressure of 1 atm. and a temperature of 37.7 oC. The sphere surface is maintained at 93.33oC. by mean of an embedded electric heating coil.what must be the rate of electrical heating in Watt to maintain the stated conditions

2. Jan 9, 2009

### brazil2200

L & G,

I still waiting for somebody to help me to solve the above problem.

Hopefully somebody will help me soon.

Thanks

3. Jan 9, 2009

### Staff: Mentor

It is inappropriate to "bump" your thread in this way. First of all, it's homework/coursework, and you have shown zero of your own work. You MUST show your work before we can be of help. I've moved your thread to a Homework Help forum from the general technical forum where you originally posted.

Second, the help you get here at the PF is all volunteer help, and it is inappropriate to expect us to help you in some minimum time frame.

So, post your work on this problem, and show us what the relevant equations are. We may be able to answer specific questions or offer tutorial help at that point.

4. Jan 10, 2009

### Delphi51

I don't know how to do it so I'll just try to get you thinking, Brazil.
The rate of heating will be related to the rate at which the sphere is cooled by the flowing air. Since you were given this question, you must know something about that and I will be most interested in what you can tell me about it! I suppose the rate of cooling depends on the temperature difference and the flow rate - but I would think also on some characteristics of air such as heat capacity and conductivity.