1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simple conversion

  1. Oct 31, 2006 #1
    If i could get anyone to double check my answers on the following it would be a big help. thanks

    On planet Z, the standard unit of length is the foose. Ann the
    Astronaut is 5.90 feet tall on
    earth. She lands on planet Z and is measure to be 88 foosi
    (plural of foose) tall. Her crew
    member Rachael is 94 foosi tall. How tall is Rachael in Earth
    measurements?

    i get 6.3 feet

    5.9/88 = 14.92

    94/14.92 = 6.3

    is this correct? thanks in advance
     
    Last edited: Oct 31, 2006
  2. jcsd
  3. Oct 31, 2006 #2
    Note the expression: y = A/x2. Which statement is most consistent
    with this expression?

    a. y is less than x
    b. if x is halved, y is multiplied by 4
    c. y is greater than x
    d. if x is doubled, y is multiplied by a factor of 2
    e. y is equal to x


    I find that A seems to be true,, but the wording on D confuses me a bit.
     
  4. Oct 31, 2006 #3
    OOOOPS, give me a moment... I'm rusty with LaTeX

    It's always a good idea to write your units down when you're doing calculations. The technique I teach is "multiply by 1"... that is, if the numerator = the denominator, the value of the fraction is one.
    [tex]\frac{3 feet}{36 inches}=1[/tex] because the numerator equals the denominator.

    Now, all you have to do is worry about the units you don't want cancelling out each step of the way.

    You could use [tex]\frac{88 foosi}{6.90feet}[/tex] as a multiplier, or you could use [tex]\frac{6.90feet}{88 foosi}[/tex] as a multiplier (to multiply by 1.

    Now, you're starting with [tex]\frac{94 foosi}{1}[/tex] If you multiply it like this: [tex]\frac{94 foosi}{1}*\frac{88 foosi}{6.90 feet}[/tex], then your units work out to foosi squared per foot. Not what you want.

    So, you multiply [tex]\frac{94 foosi}{1}*\frac{6.90 feet}{88 foosi}[/tex] And, your units work out to feet.

    for what it's worth, "5.9/88" is not "= 14.92". You meant 88/5.9
     
    Last edited: Oct 31, 2006
  5. Oct 31, 2006 #4
    [tex]\frac{5.90 feet}{88 foosi} = \frac{x feet}{94 foosi}[/tex]

    [tex]88 foosi\,x = (5.9 feet)(94 foosi)[/tex]

    [tex]x = \frac{(5.9 feet)(94 foosi)}{88 foosi}[/tex]
     
    Last edited: Oct 31, 2006
  6. Oct 31, 2006 #5
    :) Or you could do it as a proportion as Geoff did... The proportion method is easier for this type of a conversion; my method above works very well if you're converting something like miles per hour to meters per second.
     
  7. Oct 31, 2006 #6
    where did you get 6.9? is that a typo? did you mean 5.9?

    anyway, I run the numbers geoff did and I get 6.3 again..so I assum my answer is correct. thanks for the help
     
  8. Oct 31, 2006 #7
    Yes, your answer's correct.
     
  9. Oct 31, 2006 #8
    yes, 6.9 was a typo... or rather, a memory problem. :)
     
  10. Oct 31, 2006 #9
    great thanks.. one other quick question: can I just multiply 3.47 m/s/s by 5 seconds to get my speed after that amount of time? for example:

    . A European sports car dealer claims that his car will accelerate
    at a constant rate from rest
    to a speed of 100 km/hr (28 m/s) in 8.00 s. What is the speed
    after the first 5.00 s of
    acceleration?

    a.44.4 m/s b. 34.7 m/s c. 28.7 m/s d. 17.4 m/s e. 8.7
    m/s


    First I find the acceleration to be 3.47 m/s^2 now can i just times by 5? If so i get 17.4 m/s Is this correct?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Simple conversion
Loading...