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: Finding accerlation in this problem!

  1. Sep 5, 2008 #1
    To give a 16 kg child a ride, two teenagers pull on a 3.4 kg sled with ropes, as indicated in Figure 5-26. Both teenagers pull with a force of F = 53 N at an angle of 35° relative to the forward direction, which is the direction of motion. In addition, the snow exerts a retarding force on the sled that points opposite to the direction of motion, and has a magnitude of 57 N. Find the acceleration of the sled and child.

    picture: http://i232.photobucket.com/albums/ee319/reddevilzofah/05-23alt.gif

    Okay, I've tried to solve this problem and I added all the Fx. So I did 16+3.4a=-53cos35+57 Solved for a, but the answer was wrong. Can someone tell me what I did wrong and how to fix it?

  2. jcsd
  3. Sep 5, 2008 #2


    User Avatar

    Staff: Mentor

    Could you please show us each step of your work, so we can look for where you might have made a mistake?
  4. Sep 6, 2008 #3
    16+3.4a=-53cos35+57 and solved for a. Thats that work. Is the equatio wrong?
  5. Sep 6, 2008 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Two mistakes:
    (1) The total mass is 16 + 3.4. So the left side should have parentheses: (16 +3.4)a.
    (2) There are two teenagers pulling, not just one.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook