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  1. K

    Using capillary action to raise water (Is perpetual flow possible?)

    No, it isn't. There are many threads on this, I'll try to dig it up.
  2. K

    Why does rain appears to be inclined when observed from a moving car?

    Think of it this way: a raindrop moving straight down and the car moving toward it at 50mph is the same as the car being still while the raindrop moves toward it (horizontally) at 50mph.
  3. K

    Hi PF,I have been working quite heavy shifts of late being a truck

    Premade testers are readily available, usually around $100.
  4. K

    Atmosphere's Rotation

    Just to clarify, the Coriolis effect is not responsible for the direction a toilet flushes. That's a myth spread by people who care more about being interesting than being accurate.
  5. K

    Feynman exercises bead parabola accelerometer

    What is or is not the correct "default" input is completely irrelevant. A well-formed problem statement doesn't have any implicit parameters; rather, they are all explicit.
  6. K

    Feynman exercises bead parabola accelerometer

    Summary of thread: K^2 and rude man point out a completely valid flaw in the way a question is posed, and codelieb defends it anyway rather than admitting the flaw.
  7. K

    The properties of sound?

    +1 for Pythagorean!
  8. K

    How to calculate the speed of the moving point

    Essentially you will need to sample it; that is, record the position at regular time intervals. It could be every second, it could be every millisecond. It depends how accurate your output needs to be. Regardless, you can only get an average velocity, not an average speed. The smaller time...
  9. K

    Object rotation in vacuum and the Friction force

    HoI...I think I see what you are saying, but this is a very, very strange way of saying it.
  10. K

    Do springs alter velocity?

    If the direction changes, of course the velocity changes.
  11. K

    Is sound affected by gravity?

    From a practical standpoint, where we care only about earth's The molecules will experience the same gravitational force as they would when there is no sound wave at all. The exception is a sound wave with an extremely long wavelength that could move particles considerably closer...
  12. K

    Speed of a fly on an airplane

    The fly is moving faster or slower relative to the ground, depending on the direction it's flying within the plane.
  13. K

    How to caclulate the acceleration of a dropped object.

    Force = mass * acceleration. If you know the force and the mass of the object, you can find acceleration.
  14. K

    Antimatter falling upwards because of gravity?

    As it said, it's purely speculation, at least for the time being. It doesn't really make any sense to me to be honest. I say that because there's only so far you can take the "it's exactly opposite" thought process.
  15. K

    Special car jack stand for sloped grades

    Of course it's possible, you will just need a wider base for stability. I think at some point it might be easier having a very long jack which simply lifts the whole side of the car. Imagine taking two jack, separating them about 5 feet, and welding some metal beams onto them to keep them in...
  16. K

    Sorry if this is in the wrong place but im at work so i need to be

    There are many ways to interpret time. What you are asking is a philosophical question. Stephen Hawking wrong a book called "A Brief History of Time", I suggest you read it.
  17. K

    Shooting a Ball up a ramp?

    I'm a bit confused - is the ball rolling on top of a track, or sliding along a track?
  18. K

    Initial speed of a football when average speed is known

    No, your use of the equation is not correct. You have to remember that the instantaneous drag force depends on the instantaneous velocity, not an average over time. So the drag will be causing the ball to slow down, and as the velocity decreases, the drag force will decrease as well...
  19. K

    Initial speed of a football when average speed is known

    My initial thoughts are: 1) If it's a homework question, let's move it to the homework section. 2) Rules of thumb are probably not a good idea if you want an accurate answer. 3) Essentially you are asked to make some conclusion about what the graph of speed vs. time is. From the 'general'...
  20. K

    Human Weight, Work and Gravity

    Another interesting thing to think about is this: mass varies cubically with size (taken to mean one length, height, or width) while muscle strength varies according to the cross-sectional area of muslce, as a squared term. The end result is that people (and animals) who are smaller typically...
  21. K

    Force and tension

    1) I am going to go ahead and rephrase this. "Is it true that it takes less work in lifting a book by holding it near the center than by holding it at the end?" The answer is no. The amount of work done is equal to the change in gravitational energy. You can use any force you want; the...
  22. K

    Are there theories for the different sound in different volume of beaker?

    Why would you expect a change? The sound may move the atoms of the water back-and-forth on a very small scale, but it would not at all change the time-averaged movement of them. Just as shouting across a room does not cause a breeze. What we perceive as "high volume" actually carries very...
  23. K

    Are there theories for the different sound in different volume of beaker?

    The air moves, no? The air, water, and beaker are all vibrating.
  24. K

    Are there theories for the different sound in different volume of beaker?

    It's neither. The sound you hear is the vibration of the air in your inner ear. The glass, the water in it, and the air around it all vibrate. What makes you believe that your students could observe the vibration of water? Even a 500 Hz tone means the molecules move back and forth 500 times...
  25. K

    Are there theories for the different sound in different volume of beaker?

    Sort of. The properties of the glass material and the properties of the water both have an effect on the sound.
  26. K

    Are there theories for the different sound in different volume of beaker?

    Sort of. In your case it may be that simple, but certainly not in the general case. Glasses with different shapes will produce different sounds, as will striking the glass in different places. It depends on the properties of the liquid (water in this case). As someone said, the physics of...
  27. K

    Could a projectile shooting downward at near c lift 300lbs?

    Of course. The initial speed of the 300-pound object will be 1/300th the speed of the 1-pound object. There's nothing magical about a large size difference.
  28. K

    Racquetball's strange bouncing patterns

    I understand that this is due to spin. Can anyone point me to some equations that govern this?
  29. K

    Racquetball's strange bouncing patterns

    Yes, I play pool competitively as well. I am awesome at predicting these angles, but I'd like to know the equations governing them.
  30. K

    Racquetball's strange bouncing patterns

    I play racquetball quite a bit as a hobby and competitively. One thing that I have noticed, and has baffled me for some time, is that on the sidewalls of a racquetball court, the ball's angle of incidence does not equal it's angle of reflection. It instead tends to (after repeated bounces)...