Recent content by crushedcorn

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    Undergrad Determining Minimum Height to Complete a Loop

    This question was posted on Khan Academy. I attempted it after watching all of their great Work and Energy videos, but the way they arrived at the answer was way above my skill level even after reviewing the videos a number of times. Here is the question: What is the minimum height h of a slope...
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    Determining New Angular Velocity

    Homework Statement A star with mass 2.4x1030 kg and diameter 1.7x109 m rotates once every 34 Earth days. It eventually dies and becomes a white dwarf, shedding about half of its mass and contracting to a diameter of 1.9x108 m. If we approximate the star as a perfect sphere, what is its...
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    Determining speed and height on a roller coaster

    PE1 + KE1=PE2 + KE2 becomes PE=KE because, for example, at point C KE1=0 and PE2=0, so I end up using the PE1=KE2 equation. How am I confusing ΔPE with ΔKE?
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    Determining speed and height on a roller coaster

    Homework Statement One car (m=80.0 kg) tracks through the roller coaster in the following diagram. As it passes point A, it has a speed of 50.0 cm/s. a) Determine the speed at points B, C, and E b) If the speed at point D is _______, determine it's height (ignore friction) Homework...
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    Determining Coefficient of Kinetic Friction w/m, t, and v

    Thanks!
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    Determining Coefficient of Kinetic Friction w/m, t, and v

    Homework Statement A 2.0 kg block of wood slides over a horizontal surface and comes to rest in 2.5 s. If its initial velocity was 9.0 m/s, what is the coefficient of kinetic friction? Homework Equations rho=mv change in rho=F*change in t Force of friction = mu*Force normal Force normal=mg...
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    How do you determine work done wi th just mass and distance?

    Thank you and thank you! I felt like I was missing the entire concept. I feel much better :-)
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    How do you determine work done wi th just mass and distance?

    1. The problem statement, all variables and given/Information If a person pushes a 28 kg object 1.2 m, how much work did they just do? Homework Equations W=Fd F=ma The Attempt at a Solution If W=Fd and F=ma, then W=(ma)d. The farthest I can get is W=28a*1.2=33.6a. Since the motion is...