243_Physics ProblemsTechnical Physics

# 243_Physics ProblemsTechnical Physics - Chapter 8 *P8.68 If...

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Chapter 8 245 *P8.68 If the spring is just barely able to lift the lower block from the table, the spring lifts it through no noticeable distance, but exerts on the block a force equal to its weight Mg . The extension of the spring, from F s kx = , must be Mg k . Between an initial point at release and a final point when the moving block first comes to rest, we have KU U K U U ig is ifg fs f ++=++ : 0 4 1 2 4 0 1 2 22 +− F H G I K J + F H G I K J =+ F H G I K J + F H G I K J mg mg k k mg k mg Mg k k Mg k −+=+ +−= = −± =− ± 48 2 4 2 2 40 44 2 9 2 2 2 2 2 2 1 2 2 1 2 2 mg k k mMg k Mg k mm M M M mM m M m ch ej Only a positive mass is physical, so we take Mm m =− = 31 2 a f . P8.69 (a) Take the original point where the ball is released and the final point where its upward swing stops at height H and horizontal displacement xLL H L H H −= 2 2 2 2 af Since the wind force is purely horizontal, it
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## This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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