Posted: 6/22/2008 1:26:04 PM EDT
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This question came to me driving down the interstate today. Hopefully someone could shed some light. The numbers are just rough figures. This is the scenerio: A car is driving 70 MPH. Passenger in car has a slingshot and fires a marble out of window at say 25 mph. Upon impact of a road sign, would the marble be traveling at 95 MPH?? Or would it be 45 MPH?? Im trying to figure out how Newtons Laws of Motion figure into this scenerio. |
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WHICH DIRECTION did he fire the projectile? Edit, If you're talking in terms of Newton himself the pertinent law is Law III, Corollary II: The quantity of motion, which is obtained by taking the sum of the motions directed towards the same parts, and the difference of those that are directed to contrary parts, suffers no change from the action of the bodies among themselves 
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Yeah. If he's shooting straight ahead, and is in a vacuum, it would be going 95 mph. Likewise, if he was shooting straight backwards in the same conditions it would only travel 45 mph. And just to blow your mind, if he shot it at a 90 degree angle to the cars direction it would go 25 mph out and 70 mph sideways. |
What would the total speed be relative to the ground, and at what angle relative to the direction of the vehicle? 
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I'm gonna need a calculator for that 
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I'd have to relearn trig for the direction
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Those initial conditions are applicable to the Space Shuttle Door Gunner questions 
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If a F11F-1 was in a 20 degree descent and emptied it's 20mm cannon into the air, would it shoot itself down seconds later?
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Vectors are fun! Well, that is what my physics teacher said. |
I get 19.65. Inverse tangent of the opposite side over the adjacent side (25/70), so it should be inverse tangent of .36. If I remember how to work my calculator, that's 19.65 degrees. |
My bad, been about ten years since I last watched it. |
