{"id":14181,"date":"2025-02-21T14:50:48","date_gmt":"2025-02-21T14:50:48","guid":{"rendered":"https:\/\/topat10.com\/?p=14181"},"modified":"2025-02-21T14:50:48","modified_gmt":"2025-02-21T14:50:48","slug":"did-a-rock-hit-your-windshield-or-did-your-windshield-hit-a-rock","status":"publish","type":"post","link":"https:\/\/topat10.com\/?p=14181","title":{"rendered":"Did a Rock Hit Your Windshield, or Did Your Windshield Hit a Rock?"},"content":{"rendered":"


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Now the ball behaves more like you would expect. Its horizontal velocity decreases so that it falls behind the original car. But it\u2019s still not going to hit your windshield. With air drag and loss of energy on impact with the ground, each bounce is a little lower than the one before. You should be fine.<\/p>\n

Rock Out<\/h2>\n

Now say that kid drops a rock out the window. Kids! Or maybe there\u2019s a truck carrying gravel, and some of it slips through a crack. When the rock hits the road, its motion can change in a few ways. First, there’s a frictional force between the rock and the road, which will reduce the rock’s horizontal velocity. As we saw above, slower is bad.<\/p>\n

Second\u2014and this can seem weird\u2014because a rock is irregularly shaped, it’s possible that it spins and hits the pavement in a way that makes it skip up higher than it started.<\/p>\n

Hold on! Isn\u2019t that a violation of the law? You know, the law of conservation of energy? Nope, it\u2019s an energy transfer<\/em>. A rotating and moving rock has both rotational and translational (linear) kinetic energy. Some collisions can convert rotational energy to translational energy, which makes the rock bounce higher. Higher is bad.<\/p>\n

Here’s what that might look like:<\/p>\n

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