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Post by Chelsea White on Jan 31, 2006 20:11:35 GMT -5
I am having a lot of trouble posting on this site I don't think Mr. Fisher has approved the account yet. But anyways...can anyone explain number 14 on the practice test for work and energy? If you could you'd be my hero!
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Post by Mr Fisher on Jan 31, 2006 21:03:44 GMT -5
#14 is a two-part problem.... You need to use conservation of mechanical energy PLUS the work-energy theorm to solve!
Here are some hints..... (Problem is worked out on a white board in class)
1. Set the total amount of Mechanical Energy at the top of the cliff to the total amount of ME at the Bottom. 2. Write equations for each type of energy. 3. Note at the top, the rock is already moving and has an initial KE! 4. Where did that KE come from? ( the slingshot!) 5. How much energy did you put into the slingshot? In other words, how much work did you do on the rock when you pulled the slingshot back? 6. You should now have an equation with just one unknown -- the final velocity at the bottom!
Mr Fisher
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