Going Down Fast!

RAY: This was sent in by Tom Ireland and I had to mess around with it a little.

He writes:

"Where I live there are quite a few hills, many of them very steep. Some of them are quite a challenge for any vehicle, even those that are high performance. In fact, a few of these hills are so steep that I often have to ride up the whole way in low gear — especially if I happen to catch a red light at the bottom, like I did the other day.

A few days ago I found myself going not up one of these hills, but down a long steep grade. I found myself gaining speed at an alarming rate. Shifting even into the lowest gear didn't help at all and I had to apply my brakes almost the entire way down to keep from going so fast that I'd lose control and crash.

The brakes got really, really hot, but I was able to stop safely at the red light at the bottom of the hill. Here's the interesting part: There's nothing wrong with my vehicle. It's in perfect working order."

So the question is, why did I have to use my brakes to maintain a safe speed going down that hill? And why, despite the fact that I put it in first gear, did it not slow me down in the slightest?

Think you know? Drop Ray a note!

[ Car Talk Puzzler ]