brian334 Posted September 10, 2008 Share Posted September 10, 2008 Gravity makes things move, does it have energy? Link to comment Share on other sites More sharing options...
Klaynos Posted September 10, 2008 Share Posted September 10, 2008 Gravity is one of the fundemental forces. Like all forces it has a potential energy associated with it: [math]E=\frac {-GMm}{r}[/math] Link to comment Share on other sites More sharing options...
brian334 Posted September 10, 2008 Author Share Posted September 10, 2008 If a 65 lb weight fell 10 feet, what would the impact speed be? And how much force/energy would it have? Link to comment Share on other sites More sharing options...
Klaynos Posted September 10, 2008 Share Posted September 10, 2008 This looks a lot like homework... Well I don't work in imperial... So no numbers can I provide and even if I did, I wouldn't the point of homework is for you to work thew it yourself... but I shall help You can use a simplified version of the equation I used above to work out the change in potential energy: [math]\Delta E = mg \Delta h[/math] Where m is the mass, g is the acceleration due to gravity, [math]\Delta E[/math] is the change in energy, and [math]\Delta h[math] is the change in height. This energy has to be transferred into some other energy what could this be? Link to comment Share on other sites More sharing options...
brian334 Posted September 10, 2008 Author Share Posted September 10, 2008 This is not homework. Link to comment Share on other sites More sharing options...
ydoaPs Posted September 10, 2008 Share Posted September 10, 2008 This looks a lot like homework... Well I don't work in imperial... So no numbers can I provide and even if I did, I wouldn't the point of homework is for you to work thew it yourself... but I shall help You can use a simplified version of the equation I used above to work out the change in potential energy: [math]\Delta E = mg \Delta h[/math] Where m is the mass, g is the acceleration due to gravity, [math]\Delta E[/math] is the change in energy, and [math]\Delta h[math] is the change in height. This energy has to be transferred into some other energy what could this be? I thought [math]\Delta E[/math] in your equation is the change in gravitational potential energy, not the change in total mechanical energy. IIRC, in situations such as falling objects, KE1+PE1=KE2+PE2. If you choose your reference frame right, you can make some terms cancel. I'll leave that up to you. Link to comment Share on other sites More sharing options...
Klaynos Posted September 10, 2008 Share Posted September 10, 2008 I was using E for gravitational potential energy. Not best practise I'll take that but still perfectly valid. I call it that in the explanation before the equation... It will of course be exactly equal to the change in kinetic energy as shown from your equation of total energy. Link to comment Share on other sites More sharing options...
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