Recent content by superdave

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    Percent error in conservation of momentum lab confusion

    The class is a high school level course. Margin of error is beyond the scope of the class and I don't want to confuse the students too much when they already struggle with basic algebra. I might go with the % discrepancy for Δp instead, because that will reinforce the concept of conservation of...
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    Percent error in conservation of momentum lab confusion

    Okay, so I did an elastic collision with Vernier carts and magnets. The results seem pretty good. Cart one started with -0.1205 kg*m/s ended with +0.1027 kg*m/s Cart two started with +0.1174 kg*m/s ended with -0.1118 kg*m/s So Total before = -0.0031 kg m/s and total after = -0.0091 kg m/s. If...
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    I Weight of a relativistic particle

    And assuming the box is a perfect thermal insulator (I guess sealed after the gas was heated), is there anyway to tell whether it is a box of x hot gas particles or y cold gas particles?
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    I Weight of a relativistic particle

    Well, more specifically, I'm asking whether or not the effect that was once referred to as a the deprecated term "relativistic mass" is indistinguishable from rest mass in certain situations such as the one I described above. I understand that there are legitimate reasons for defining rest mass...
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    I Weight of a relativistic particle

    If I were able to accelerate a particle to relativistic speeds, then capture that particle in a box in such a way that it kept its speed, then weighed that box, would it weigh more than the box + rest weight of the particle? Would it exert a gravitational field greater than that of the box with...
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    B Recent question on NYS regents exam, is it accurate?

    So I guess my point is that it's a bad question.
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    B Recent question on NYS regents exam, is it accurate?

    A beam of which of the following will produce a magnetic field? Gamma rays X-Rays Neutrons Protons Now, the answer they want is protons, to emphasize that moving charged particles create magnetic fields. But is that really accurate? Do moving photons NOT consist of a changing magnetic field...
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    A powered toy car moving at a constant speed

    So if I were to take this toy car and What would demonstrate the lack of or existence of traction? If the car were to roll at a constant speed onto a near frictionless surface in a vacuum, moving normal to the interface, if there was no traction then it should keep rolling at the same speed...
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    A powered toy car moving at a constant speed

    Okay, so please help settle a dispute. A toy car is moving at a constant speed of 1 m/s. The car is powered by a battery. Now, when the car is going at a constant speed, there is obviously no net force on the car. The dispute comes when trying to draw a FBD. Is there friction (traction)...
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    New paper says universe not expanding - should it be taken seriously?

    In interviews, they make a strong implication that the universe is not expanding.
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    New paper says universe not expanding - should it be taken seriously?

    Eric J. Lerner, long time Big Bang opponent, has published a paper that I don't really understand but claiming it indicates the universe is not expanding. Can anyone actually help to point out why or why not his observations should be given consideration? It was Published in Int. Journal of...
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    Cool examples of radiometric dating?

    Apparently, thanks to nuclear bomb testing in the 40s, C-14 dating can be used on recent teeth to date someone's year of birth within 3-6 years, which is helpful when trying to identify bodies. There is a new method testing the eye that is even more accurate, but only useful within 3 days of...
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    Cool examples of radiometric dating?

    So, I know that C-14 dating is being used now to solve crimes/identify bodies. Any other examples of it being used for things besides dating really old rocks/fossils? I'm teaching an Earth Science class and I want to show them a few cool articles.
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    Variable formula question Why does W2 = 24W1?

    The Work-Kinetic Energy Theorem states that Work = Change in KE. Try going from there.
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    What is the Speed of Gravity?

    This can be conceptualized as two people swinging around each other holding a tense rope. The tension in the rope is felt by both parties all the time they swing. But if one person tugs or let's go, it will take some amount of time for this to be felt by the person on the other end. Now, for...
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