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A Man & His Horse......................................
Man: Giddy up! Pull the cart so we can get going.
Horse: For me to pull the cart would be a futile effort. You see, if I pull on the cart, the cart will pull back on me. By Newton's 3rd law... The forces are equal and opposite so they'll cancel out. A zero net force wont work.
Man:(thinking...) I don't care bout the force exerted on you! I'm interested in the force you exert on the cart. You pull the cart and I guarantee it will move.
Horse: But how can I move forward when the cart pulls backward on me.
Man: (thinking...) just push backward on the ground. By Newton's 3rd law, the ground will push forward equally on you. Then I'll simply follow.
Man: Hahaha....The ground is doing a great job!
The first step in the acquisition of wisdom is SILENCE, the second is LISTENING, the third MEMORY, the forth, PRACTICE and the fifth is TEACHING others!
The worst part is I actually took the time to think about why the horse is wrong...basically, the forces are equal, but their masses are different and as a result the resulting accelerations are not equal, and there is net acceleration. I think. I tried to scrub most of that from my brain the moment I was done with it.
Assuming there is no give, then the acceleration is the same since they are connected. If the horse accelerates, then the cart accelerates then same amount, and they will have the same velocity. What is different in the energy if the masses are different (1/2 m v square).
They have to accelerate to have velocity for kinetic energy in the first place. They both end up with the net acceleration, but the accelerations due to the force between them is different for both objects.
Is it wrong to tell a muslim that his wife is starting to look a bit porky?
".45 ACP - because shooting twice is just silly" - JSOP, 2010 ----- You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010 ----- "Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass." - Dale Earnhardt, 1997
Last Visit: 31-Dec-99 18:00 Last Update: 25-May-17 20:15