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!

Work and energy difficulty

  1. Apr 17, 2008 #1


    User Avatar

    [SOLVED] Work and energy

    Hello, I've been having difficulty with this question...
    1. The problem statement, all variables and given/known data

    A 25.6kg child pulls a 4.81kg toboggan up a hill inclined at 25.7° to the horizontal. The vertical height of the hill is 27.3 m. Friction is negligible. Determine how much work the child must do on the toboggan to pull it at a constant velocity up the hill.

    2. Relevant equations


    3. The attempt at a solution

    I tried using the equation above...and i tried adding the masses ...I got the wrong answer. The force, I used F=mg
    w=mgd cos (angle)
    =(4.81) (9.8) (27.3) cos (25.7)
    =1.15 x 10^3 J
    the answer 1.29 x 10^3 J but i'm not geting that...:confused:
  2. jcsd
  3. Apr 17, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Welcome to the forums ka7,

    HINT: What is the change in gravitational potential energy of the toboggan? (Much easier :wink:)
  4. Apr 17, 2008 #3
    You should recheck what the D in your formula means. It is presumably NOT the vertical height of the hill.
  5. Apr 17, 2008 #4


    User Avatar

    Thanks, i figured out what i was doing wrong:smile:
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Work and energy difficulty
  1. Work and energy (Replies: 0)