Recent content by defetey

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    Simple energy question, but getting different results with different methods

    Homework Statement A linear elastic spring is 0.15m long. When the upper end is held in the hand and a 0.5kg mass is suspended from the lower end, its length becomes 0.22m. What is the spring constant?Homework Equations E_{E}=\frac{1}{2}kx^{2} \vec{F_{spring}}=kx \vec{F_{G}}=mg E_{G}=mgh...
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    Conservation of energy and momentum for a bullet fired into a block

    Homework Statement An 8 g bullet is fired into a 2.5 kg block initially at rest at the edge of a frictionless table of height 1 m. The bullet remains in the block and lands 2 m from the bottom of the table after impact. Determine the initial speed of the bullet. Answer: 1392 m/s...
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    Newton's Third Law and gravity

    But if something was between them, would it experience 10 N of force (5 from the book and 5 from the Earth)?
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    Newton's Third Law and gravity

    This is not really a homework question, just a question I came up with. If the Earth is pulling, for example, a book with a force of 5 N, that means, due to Newton's 3rd law, that the book is also pulling the Earth with a force of 5 N. Does this mean the total force between them is actually...
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    I'm not sure which method is correct (statistics)

    Yea it will take a lot longer, but the answer won't be 0 for sure though. Like I said, how could the expected payout be zero when there IS a chance they will pay SOMETHING out. That's what I've done for every other question, for http://en.wikipedia.org/wiki/Expected_value#Examples"
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    I'm not sure which method is correct (statistics)

    But that's enough to find the probabilities using a binomial distribution, isn't it? Ex, to find the probability that one passenger is overbooked: =252C241(.95)^241(.05)^11
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    I'm not sure which method is correct (statistics)

    Homework Statement The Attempt at a Solution The textbook says the answer is 0. I think they get that by saying that 5% of 240 is 12. So the plane is overbooked by 12. So there are 252 people booked on the plane. Then the binomial expectation is (252*0.95)=239.4. Which means they payout...
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    Lenz's Law: Direction of Flux & Current

    Homework Statement I don't have the question with me, it was on a test I did. It was something like this though: A coil is placed vertically on a table. The magnetic field there is also vertical. If the magnetic field is suddenly switched off, in which direction would the current in the...
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    How Does Voltage Influence Current Flow in Circuits?

    So I'm sort of confused by voltage and I hope these will clear it up for me; 1) Why can parallel circuits only have equal voltage drops on both sides? Say a voltage of 5 is entering the parallel circuit, and one side uses 5 and the other uses 4, why is that not possible? 2) If voltage is what...
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    Calculating Average Force and Mass: Weightlifting and Shelf-Moving Examples

    A world champion weight-lifter does 5000J of work lifting a weight from the floor to a height of 2m. What is the average force exerted on the weight? What is the mass of the weight? So I got the first part, it's 2500N. But how would I find the mass given just that much information? And for...
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