Calculating Acceleration of a Sled on an Incline with a Pulling Dog

[ThatDude]

Homework Statement

A dog pulls the rope of a 50 kg sled up a hill with an incline of 20° above the horizontal. The rope is directed 30° from the slope and the dog exerts a force of 200N on the rope. The force of friction is 50 N. What is the sled's acceleration?


2.The attempt at a solution

Fnet = ma

(Fapp) - (Ffriction) - (Fgx) = (50)(a)

(200N cos30) - (50N) - (50 kg * 9.81 m/s/s * sin20) = (50) (a)

a = -0.89 m/s/s.

Therefore, the sled is going down hill?!

 

[jonjacson]

I did the problem and got the same results, I cannot help.

You should change your dog :), or maybe we are doing some mistakes, who knows.

 

[lendav_rott]

The pooch is too weak. It makes sense too, though, he has to pull a 50kg sled with only an initial 200N of horsepower to work with.

 

[jonjacson]

Even without the 30º the dog cannot pull the sled, maybe the teacher shows this to explain why you need a bunch of dogs pulling the sled :) .

 

[ThatDude]

Thanks guys. I guess i did it correctly.