A grade 12 physics dynamics problem

  • #1

Homework Statement


A boy drags his 80 n sled at a constant speed up a 15 degree hill. He does so by pulling with a 35 n force on a rope attached to a sled. If the rope is inclined at 35 degrees to the horizontal, what is the coefficient of kinetic friction between snow and sled

At the top of hill, he jumps on sled (weighing 50 kg, the boy) and slides down the hill. What is his acceleration?

Homework Equations



Fnet= ma

Ffk = mew fn

And so on, so forth.

The Attempt at a Solution


[/B]

I drew a FBd, including angles, and force locations, but I do not know how to use the angles to find the required forces.


As well, as a general question, how do you use angles in the diagram to find things?
 

Answers and Replies

  • #2
My main problem is that I know the Fg, which is ma (9.8)

After that, I get slightly lost due to the angles, and am unable to find even the most basic fn.
 
  • #3
haruspex
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I drew a FBd, including angles, and force locations, but I do not know how to use the angles to find the required forces.
if you can't post the diagram, at least try to describe it. What forces operate, what magnitudes and what directions?
Invent symbols for all values so that the algebra can be done symbolically. Only plug the numbers back in at the end.
 

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