A funny thing happened to me at the store the other day. I was looking to buy socks for my son in the aftermath of what appeared to be a shopping free-for-all. Nothing was left on the shelves and everything remaining was in disarray. Finally, desperate, I located a ripped-open bag of socks with only 5 of 6 pairs remaining. Thinking that no one else would buy such an item – and that I might be able to get a good deal – I asked the sales clerk how much of a discount I could expect.
"Ten percent," came her prompt reply.
I stared at her. Ten percent? I thought. That’s only 1/10 off the original price. One-sixth of the socks, or more than 15% of the merchandise, is missing!
Needless to say, I took a pass on her offer. But the take-home lesson when solving equations – and this is true for science as well as math – is to always check your answers to make sure that they are practical.
Let’s say you are trying to figure out how fast an object is going and you are solving for speed. Don’t wind up with a negative number! (Or, as happened in one of my husband’s economics classes, don’t solve a pricing equation and give a negative number. It’s rare that a store will pay you to take their stuff!) John Hawley, of NEWTON’s Ask a Scientist presents a nice post - Negative Velocity - on this topic.
Learning complex concepts in science and math can seem daunting, but always remember to use that reality check! (It could even save you some money.)