- #1

moy13

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## Homework Statement

When an airplane is in flight with the engine running, it is acted on by

four forces. These are:

(i) The weight of the airplane.

(ii) The thrust provided by the engine, which pulls the airplane forward in the direction it is moving.

(iii) The drag (air resistance), which pulls on the airplane opposite to the direction in which the airplane is

moving.

(iv) The lift provided by the wings, which pulls on the airplane in a direction perpendicular to the direction in

which the airplane is moving.

Fred has just earned his private pilot license. He is

flying at an altitude H in a Piper Warrior, a small

single-engine airplane of weight W. Suddenly,

without any warning, the engine stops. The airplane

begins to descend in a steady glide at a constant speed

v through the air, with the nose of the plane pointed

below the horizontal. In the glide, the magnitude of

the total drag on the airplane is D. What horizontal

distance will the plane glide before Fred has to

execute an emergency landing?

To test your general expression, evaluate for the case W = 10,000 N, D = 1500 N,

v=40 m/s, and H = 2000 m.

Does your numerical answer seem reasonable?

## Homework Equations

components of velocity:

Vx = Vox * cos (a)

Vy = Voy * sin (a)

tan (a) = opposite / adjacent

sin (a) = opposite / hypotenuse

cos (a) = adjacent / hypotenuseI'm not sure if this one is relevant to the problem:

Y = Yo + Vo*t

## The Attempt at a Solution

I know I'm supposed to find the angle in which the plane is falling, but how do I do that?

I also know the forces remaining when the engine shuts off are the drag, the lift, and the weight, but these forces cancel since the velocity is constant. Because there is a constant velocity and because the forces canceled each other the plane is not in projectile motion.

The direction of the lift vector is perpendicular to the velocity and that makes lift perpendicular to drag as well. The weight is just straight down.