Recent content by sean-820

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    Special Relativity and spacecraft

    I solved it. The answer is 75 hours. I think it was more the wording of the question that messed me up. Escape velocity wouldn't matter as it isn't necessarily orbiting earth.To solve, i just used the formula given twice. First time to sub in the initial velocity and time to get the stationary...
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    Special Relativity and spacecraft

    The spacecraft can't be traveling "around" the Earth at this speed if you mean that it is circling the earth.Yes its path is around Earth at that speed. Does 32H mean 32 hours? yesAre the events at the same location on the earth?yes Can you give us the exact wording of the question? A...
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    Special Relativity and spacecraft

    Homework Statement A spacecraft is traveling around Earth at 1.8x10^8m/s relative to the earth. If the spacecraft determines two events on Earth to be 32H, what time interval would they find if the spacecraft is traveling at 2.82x10^8m/s? Homework Equations delta Tm=delta...
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    Minimum Length for Safe 1000kg Plane Landing on 2000kg Barge

    The main thing that I'm not sure on is the impulse = change in momentum. For the mass would i have to do m1 or the total m1+m1 mass?
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    How Do You Calculate Force for a Marble to Complete a Loop in a Rollercoaster?

    I would use F=(mv^2) /r m=mass v=velocity r=radius You can find the minimum force needed by F=mg then sub into the first equation. This is assuming the radius is constant. Real rollercoasters are clothoid loops (oval) , not circles if you wanted to do an actual roller coaster. These...
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    Minimum Length for Safe 1000kg Plane Landing on 2000kg Barge

    Homework Statement 1000kg plane lands on a 2000kg barge on in a calm ocean. The only frictional force is equal to one quarter of the planes weight. What must the minimum barge length be to land safely if it hits the deck at 50m/s. Also there is no water friction/resistance. Homework...
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    Circular motion-mass and radius given- finding frequency and force

    Thanks a lot. I got the answer a)0.39Hz and b) 3.9N I think i was over thinking it and totally forgot that if the minimum frequency would be at the top when Fc-mg=0
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    Circular motion-mass and radius given- finding frequency and force

    Homework Statement A 0.2kg mass is tied on the end of a 1.6m long string and whirled around a circle that describes a vertical plane. a) What is the minimum frequency of rotation needed to keep the mass moving in a circle? b) Calculate the maximum tension in the string at this frequency...
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    Projectile motion- only distance is known

    would mgh=0.5mv^2 work too I am assuming. Mass can cancel out. and i know gravity and height so the only variable would be vertical component. Now that you point it out it seems much easier as i was trying to find the horizontal component first. The question isn't worded the best as it could...
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    Projectile motion- only distance is known

    Would the shortstop not be 3m-3mm tall? Other formulas: v=d/t v2^2=v1^2+2a(d) quadratic formula- (-b+- sqrt(b^2-4ac))/2a but i don't have enough info to sub in. I looked in my notes and textbook and the formula i gave is the one we are using. i didnt see any other formulas other then...
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    Calculating Mass in a Momentum Conservation Problem

    I think that's right. If one was 200lbs then that one would blow through the other guy and not stop at the point of collision like i think the question is saying.
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    Projectile motion- only distance is known

    Homework Statement A baseball, thrown from shortstop position to first base travels 32m horizontally, rises 3mm and falls 3m. Find the velocity of the ball. Homework Equations d=v(t)+0.5(a)(t)^2 The Attempt at a Solution So i know horizontal motion will be a constant velocity...
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    Acceleration problem-how to incorporate head starts?

    thanks so much for your help and taking the time to clarify, it was appreciated and now i feel i could answer more questions like this easily with no help
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    Acceleration problem-how to incorporate head starts?

    Edit: Whoops, still a couple of loose ends to tie up: 1. Which solution, t=4 or t=8, or both, is the correct answer? t=4s 2. How far does the pedestrian have to run to catch the bus? 24m Buses velocity when caught is 4m/s. (v2=v1+a(t)) Would t=8 or x=8 matter since the x-axis is t? Or...
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