While working, I occasionally think of the physics principles involved in whatever I'm doing right now, say I'm demolishing a wall. Naturally, Newton's Third Law of Motion floats around in the back of my head whenever I'm using the rotary hammer (a type of jackhammer), and how it makes my arms sore. Much of the reaction force is mitigated by the weight of the hammer itself, but the concept backfires when you have to pound locations higher than you.
I was having a rough time shoveling sand, thinking about the shovel being a Class 3 lever, when I realise I've also been unconsciously working the shovel using the couple mechanic. I had my left hand pull the shovel up, while my right hand pushes down on the handle.
|A poorly-drawn shovel|
Green Arrow : Force that left hand applied
Pink Arrow: Force applied by the right hand
Black Dot: Centre of rotation.
Get the picture? (no pun intended)
These thoughts made me realise how much I enjoy physics, and how good it would be to have a physics degree.
P.S. What is it with Physics students/teachers and their lousy drawings?