How can I calculate the work needed to pull a toboggan up an inclined hill?

[ka7]

[SOLVED] Work and energy

Hello, I've been having difficulty with this question...

Homework Statement

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.

Homework Equations

W=FD COS (ANGLE)

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...

 

[Hootenanny]

Welcome to the forums ka7,

HINT: What is the change in gravitational potential energy of the toboggan? (Much easier )

 

[Pere Callahan]

You should recheck what the D in your formula means. It is presumably NOT the vertical height of the hill.

 

[ka7]

Thanks, i figured out what i was doing wrong