Mechanics problem involving trig and forces.

[chrisrock]

A fully loaded Cessna-182 airplane of mass 1260 kg has an engine failure when flying with an airspeed of 126 km/h at an altitude of 2870 m on a calm day. It then glides at a constant glide angle (which is the direction of flight below the horizontal) towards a safe landing at this constant speed of 126 km/h experiencing a drag force of 1280 N that opposes the direction in which the plane is moving.
Please use: g = 9.81 m s-2

[PLAIN]http://img805.imageshack.us/img805/5625

I would like to know what equations and values i should be using to find the glide angle of the plane.

I tried using the forces given, weight and drag, with trig but as I know that the drag force is not a component force of weight I didn't have high hopes. So of course i got the wrong answer.

Will upload the working once I draw the diagram I drew in paint.

I know the answer is 5.94 degrees.

Thanking you in advance. Been banging my head around this problem I just don't see what to use to work out the glide angle.

 

[Lok]

If something is falling, what equations do we use?

If you have a Force (be it Drag) exerted over a distance what can you get out of it?

 

[chrisrock]

hey lok i presume we are talking about the kinematics equations. I will have a look back and report to you in a min but i don't see how i can get the angle using those equations.

actually its late in NZ so imma c this tomorrow but i think i got it, just need to manipulate the equations properly.

 

[Lok]

Well you know the speed it moves forward (or at the unknown angle) and all you have to find is the speed it is falling considering it is dropping at a constant speed attracted by gravity and slowed down to a constant speed by friction.

And then there is a bit of Trig...

 

[chrisrock]

Hey lok sorry for the late reply i did work it out last night. just been busy and haven't been able to put it up i will in an hour or 2 though thanks for the help.

 

[Lok]

Hey lok sorry for the late reply i did work it out last night. just been busy and haven't been able to put it up i will in an hour or 2 though thanks for the help.

Np. Anytime.

 

[chrisrock]

I used the drag force divided by the weight force, and then took the inverse sin of the answer.

Θ = sin-1 ((drag force)/(mg))


Unfortunately i can't explain y i used this as that will require me to do a diagram which i find time consuming, and as I'm short on time i can't help it SORRY !