Newton’s Three Laws

The following is a true story that I’ll use to engage my students as we’re about to begin a section requiring the use of Newton’s Second Law.

One night, just before I was about to fall asleep, my wife asked if I could double-check that the front door was locked. Here was the ensuing conversation.

Me: “I’m tired… Newton’s First Law.”

Her: “Newton’s Second Law.”

Me: “Newton’s THIRD Law!!!”

In case you need a translation into plain English:

Me: “A body at rest tends to remain at rest. I don’t want to get up.”

Her: “Force equals mass times acceleration. Then I will push you out of bed.”

Me: “For every action there is an equal and opposite reaction. Then you’ll get pushed out of bed too!”