1. Limited time only! Sign up for a free 30min personal 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!

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


    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


    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


    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