What makes the vehicle whine when starting the car?

Anytime I accelerate I hear a high pitched whining coming from the car -- if I take my foot off the gas pedal the whining stops. I have been told it is the serpentine belt -- is this right.

Hello,

The other day my car was supposedly running fine. I drove it to work, it was fine. When I truned it on to leave, it had this loud sort of whining/wheezing noise coming from under the hood. The noise is now continual, and adjusts in level as I accelerate. I just had the fan replaced, and that didnt help it at all. The nechanic says he has no idea whats causing it, so I'm not sure if I'm due for a break down on the road, or if its nothing serious.

Would you happen to have any ideas?
Thank you

My suv is making a whining noise and is straining to accelerate. What could be the problem?