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Homework Help: Questions on the basic principles of physics.

  1. Nov 8, 2007 #1
    Really isn't involving problems, just principles of physics.

    What are the units of velocity?

    Im aware of m/s, but I hear there are more.

    What is the value of "G"?

    If an object starts from rest and travels a distance d in t sec, what equation may be used to find its acceleration?

    Really all I need help on.
  2. jcsd
  3. Nov 8, 2007 #2
    Average velocity is the change in unit distance per the change in unit time. (m/s, mph, feet/sec. km/h, etc).

    Instantaneous velocity is the rate of change in position per the rate of change per unit time. Same units.

    The value of g is 9.8 [tex]\frac{m}{s^2}[/tex] or 32.2 [tex]\frac{ft}{s^2}[/tex]

    Equation of motion:

    [tex]x=x_0+vt+\frac{1}{2}at^2[/tex] Solve for a
  4. Nov 8, 2007 #3
    Hey, I made a new thread.

    I dont think you properly understood the question.

    See my new thrad.
  5. Nov 8, 2007 #4
    And I know the value of G is 9.8 we

    but It would be 980cm/m2

  6. Nov 8, 2007 #5
    Centimeters per meter-squared? No. In centimeters, it would be [tex]\frac{cm}{s^2}[/tex]
  7. Nov 8, 2007 #6
    Velocity could be measured in any distance units divided by any time units.

    The acceleration caused by Earth's gravitational field, at the surface of the Earth, is normally denoted by g (not G) and is 9.81 meters per second per second.

    If your object is accelerating at a constant rate then the equation to use is
    d = 0.5 at^2
    a = 2d / t^2
  8. Nov 8, 2007 #7
    Yra I know it is 9.80 meters, but they want to convert it into centimeters. So it would b 980?
  9. Nov 8, 2007 #8

    Yes. Use google as a calculator. Put in the following "9.8 meters to cm", click "search" and you get out the following: 9.8 meters = 980 centimeters

    It even does automatic unit conversions. Put in "9.8 m + 32.2 ft", click "search and get back:

    (9.8 meters) + (32.2 feet) = 19.61456 meters

    How about this:

    "50 mph + 10 m/s" "search"

    (50 mph) + (10 (m / s)) = 32.35200 m / s

    Pretty damn cool, huh?
  10. Nov 8, 2007 #9
    Velocity is loosely a change in a position (distance) divided by the time interval that it took to change position.

    So it will always be a distance over a time. Big G is called the gravitational constant( [tex]6.673*10^-11 \frac{m^3 s}{kg}[/tex]). Little g is acceleration due to gravity ([tex]GM/R^2[/tex]). On the surface of the earth we can roughly measure it to (9.80m/s^2)
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