Recent content by Delphi51

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    Exploring the Mysteries of Laser Physics

    1. I can't think of an answer! I see no limit on the direction a photon may go. 2. This must be related to the laser characteristic that all the waves are synchronized in phase and reflect from the mirrors. How can a wave reflect twice, travel twice the cavity length and emerge in phase a whole...
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    Is acceleration vector or scalar?

    Hi Jumbogala - I was also a high school physics teacher and I saw what you describe in textbook lists of scalar and vector quantities. There are separate terms for speed/velocity (though the word velocity is often used for both), but acceleration was listed twice because there is no separate...
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    Is Thinking Distance Proportional to Speed in Car Braking?

    The thinking distance at 20 mph could be 6 m if the thinking time happens to be 0.671 s. The thinking distance depends on the thinking time, which isn't given. It could be deduced from some other information such as the total stopping distance including the thinking distance for some speed...
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    Question about Projectiles being launched horizontally

    There is a reason why the high school physics demo of shooting a steel ball horizontally at a falling light bulb is enjoyed and remembered by most students. As long as the ball in 2D motion and the bulb in 1D motion start simultaneously, the ball always hits the bulb no matter what speed it is...
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    Angular kinematics: determining satellite orbital radius

    The question asks for the "orbital radius", suggesting that you should assume a circular orbit. This means the rocket does not go straight up but turns horizontal during acceleration so that it gains a large horizontal velocity. Without knowing how much of the thrust is horizontal and how much...
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    Magnetic Reductor: Questions & Answers

    I see your point. Like an automatic transmission torque converter. When a lot of output torque is needed, you have to run the engine faster to provide the necessary output power. However, with the magnetic coupling my mind sees catastrophic failure when the inner ring goes out of sync with...
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    Magnetic Reductor: Questions & Answers

    If the inner rotor is turning steadily at constant angular velocity, I think the outer one will turn steadily at the same angular velocity. I picture an equilibrium where the N on the inner magnet is just a little closer to the outer N on the forward side than to the outer N on the reverse...
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    2 questions regarding circular motion and Newton's 1st Law

    Wow, great questions! 1. Circular motion is complicated because the car on a curve is constantly changing direction. If you picture the car at the moment it is going straight north but turning west, then the car is accelerating in the west direction. It's component of velocity in the west...
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    Help! Physics Problem: Find Theta for 1000m Target

    These models can be fun. No calculus needed. The idea is to calculate the forces on the bullet immediately after leaving the gun (time 0). Use your basic formulas for uniform accelerated motion to find what those forces do to the velocity and position over a small time interval. This gives...
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    Buckinghams PI-Theorem

    Are you thinking of using conservation of energy or a forces/acceleration/velocity approach? It would be interesting to try it both ways.
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    Kinematics Equations and a Cliff

    I really like the two headings for horizontal and vertical parts of the motion in that example. That is a great first step in any two dimensional motion problem. The second step is to identify which part is accelerated motion and write the appropriate formulas.
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    Kinematics Equations and a Cliff

    The v and vo are in the horizontal motion formula with no acceleration. We used to write d = vt in high school. This v is the speed of the car you are trying to find.
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    Kinematics Equations and a Cliff

    I don't see any parts in the question posted. What is part C?
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    Kinematics Equations and a Cliff

    The strategy is certainly correct. I get a much smaller answer, though. I find your horizontal motion distance formula confusing with the two velocities and division by 2. The horizontal velocity is constant; why not just call it v? Try running it through that way!
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    Special Relativity and time dilation

    Yes, you are right on track and the factor has no units because it is a ratio of two times. I get a different number for the answer. I'm old and out of practise so you are probably correct, but do run it through again to check.
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