Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Perpendicular Forces, Acceleration and Mass Problem

  1. Feb 1, 2007 #1
    1. The problem statement, all variables and given/known data

    Two perpendicular forces, one of 45.0 N directed upward and the second of 60.0 N directed to the right, act simultaneously on an object with a mass of 35.0 kg. What is the magnitude of the resultant acceleration of the object?

    A. 8.68 m/s^2
    B. 3.00 m/s^2
    C. 5.25 m/s^2
    D. 1.41 m/s^2

    2. Relevant equations

    F = ma to a = F/m

    3. The attempt at a solution

    a = F/35.0 kg

    I simply don't understand what to do with the two forces? Should I draw a diagram? Please help me!
     
  2. jcsd
  3. Feb 1, 2007 #2

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    The acceleration on the particle will be due to the resultant force. How can you calculate the resultant of the two forces? Draw a diagram-- it may help you.
     
  4. Feb 1, 2007 #3
    Would I use the Pythagorean Theorem?

    I did (45.0)^2 + (60.0)^2 = c^2
    c = 87.46 N

    I plugged that into a = 87.46 N/35.0 kg, and got an incorrect answer.

    What did I do wrong?
     
  5. Feb 1, 2007 #4

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    Your calculation for c is wrong. Try checking it again.
     
  6. Feb 1, 2007 #5
    Sorry, c is 75 Newtons.

    a = 75 N/35.0 kg
    a = 2.14 m/s^2

    Am I missing a step?

    (Thanks for helping me so far)
     
  7. Feb 1, 2007 #6

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    Well, that's the answer I get. Either we're both overlooking something, or there's a typo in the question (I'd say that the latter was more likely!) Are you sure you wrote down the question and answers correctly (is there a possibility that the mass is 25kg?)
     
  8. Feb 1, 2007 #7
    I checked and that is the problem. Hmm. Well, thank you for helping me! :)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook