FROM APPLE TO DINOSAUR
Ah, an apple. It’s loaded with organic molecules. Let’s pick one, and select two carbon atoms in the chain. And why not give them names? They will be our friends for a substantial period of time. For simplicity, I will go with Jack and Jill.
The apple in which Jack and Jill currently reside is hanging from a low branch of an apple tree. It is in equilibrium, since the force of its mass acted upon by gravitational acceleration (F = ma) is being counteracted by the normal force being exerted upon it by the tree branch via the stem of the apple.
This is what is known as unstable equilibrium. The apple is quite ripe, hence the stem’s ability to transmit forces is quite weak. Given one large enough external force to act on the system, the stem will snap and the apple and branch will be free to react separately to the forces acting upon them.
Enter a gust of wind of constant velocity. It exerts a force on the tree branch (the mass of the air coming into contact with the branch, times the acceleration of the branch as it goes from zero motion to an altered position due to the wind pressure). This is slightly too much for Jack and Jill’s apple to remain aloft. In a split second, the horizontal force applied to the stem snaps it, and the apple is suddenly free to act alone under the force of gravity.
Who should be sitting underneath the tree but a small plant eating dinosaur, appropriately of the genus Magnus Isaacus Newtonosaurus. The dinosaur experiences a sudden force exerted by the apple (accelerating downward at 9.81 meters per second per second) as it hits its skull and the apple comes to a stop.
At this juncture, the dinosaur (quite unaware of the physics that brought about this free serving of food) proceeds to eat the apple and go about his business.
Jack and Jill are processed by the dinosaur’s digestive system into an ATP cell inside the its muscular system.