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Date: 3-10-2016
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Date: 26-10-2016
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Date: 25-10-2016
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Cartoon Free Fall
So many of us in our youth learned the laws of nature from cartoons. Some of us are still learning from cartoons! The cartoon character steps forward off a cliff and remains there in suspension until realizing the situation, then the acceleration downward begins. As you recall the scene, what violations of physics can you discern?
Answer
When the cartoon character steps off the cliff, the fall should begin immediately, of course. The natural path is essentially a parabola, with approximately free-fall acceleration downward and a constant velocity horizontally. Even a cartoon character must have some mass; otherwise the character could not exert a force on anything, including the ground being walked on. Unless the upward buoyant force of the air balances exactly the gravitational force downward, no cartoon character stepping off the cliff would remain in suspension at the height of the cliff. Even if the buoyant force was sufficient, why would its upward push disappear suddenly to allow the character to free fall?
We should see the character accelerating downward with ever-increasing speed unless the terminal velocity is reached or the buoyant force balances the weight. The collision at the bottom is also subject to analysis. To prevent this sudden collision, sometimes another character is able to run down from the cliff top just in time to catch the falling character. And sometimes we even see another person falling with a greater acceleration downward to arrive in time to catch the victim! If the fall is nearly at the free-fall acceleration, the runner must be mighty swift! There are measured examples of skiers going down Mount Fuji with accelerations greater than the free-fall acceleration, but no runner has achieved this feat yet. And yes, an anvil always has a greater acceleration downward than any other object (sure!)!
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