# Thread: Sledge on a slop problem -

1. ## Sledge on a slop problem -

A ramp that is 3.25m long leads up to a platform which is 1.25m high. A cubic packing
case of side length 1m that weighs 50kg stands at the top of the ramp. It is held in position
by a rope held parallel to the ramp.
(a) If the coefficient of static friction is 0.35, what is the tension in the rope?

I am trying to understand the solution to this problem, but I don't understand the part where values of

$\displaystyle sin \theta = \frac{5}{13}$

$\displaystyle cos \theta = \frac{12}{13}$

how were these values obtained?

2. ## Re: Sledge on a slop problem -

Originally Posted by Tweety
A ramp that is 3.25m long leads up to a platform which is 1.25m high. A cubic packing
case of side length 1m that weighs 50kg stands at the top of the ramp. It is held in position
by a rope held parallel to the ramp.
(a) If the coefficient of static friction is 0.35, what is the tension in the rope?

I am trying to understand the solution to this problem, but I don't understand the part where values of

$\displaystyle sin \theta = \frac{5}{13}$

$\displaystyle cos \theta = \frac{12}{13}$

how were these values obtained?
How is sine obtained in a right triangle? What about cosine?

If that doesn't make sense, draw a right triangle with leg lengths 5 and 12, and answer the following questions:
(a) What is the length of the hypotenuse?
(b) Consider the acute angle adjacent to the 12-length side. What is its sine? (You should not need a calculator for that.)
(c) What is its cosine?

3. ## Re: Sledge on a slop problem -

Hello,

I know it was derived from drawing out a right angled triangle, but I still dont understand what numbers to put in?

As far as i can see, in only know the length of one side? v = 1?

where did 5 and 12 come from in the first place?? Thats what i dont get

4. ## Re: Sledge on a slop problem -

Originally Posted by Tweety
A ramp that is 3.25m long leads up to a platform which is 1.25m high. A cubic packing
case of side length 1m that weighs 50kg stands at the top of the ramp. It is held in position
by a rope held parallel to the ramp.
(a) If the coefficient of static friction is 0.35, what is the tension in the rope?

I am trying to understand the solution to this problem, but I don't understand the part where values of

$\displaystyle sin \theta = \frac{5}{13}$

$\displaystyle cos \theta = \frac{12}{13}$

how were these values obtained?
from what I can tell they are wrong.

You're given the opposite side is 1.25, and adjacent side 3.25.

a 5/12/13 triangle has opp/adj = 5/12 = 0.417

so this ramp is not 5/12/13.

5. ## Re: Sledge on a slop problem -

Originally Posted by Tweety
Hello,