Question

DC 10 Jet liner is flying straight and level at 21,000 feet at a constant speed of 600 miles/hour. The engines are delivering a combined thrust of 100,000 lbs. What must the drag force of air be?


a. _____________


The aircraft with its passangers and cargo weighs 500,000 lbs. What is the total lift force acting upward on the plane to keep it in the air?


b. ________________

Answer 1

ghere ,

let the drag force by air is Fd

as the plane is moving with constant velocity

net force on the plane will be zero

Fd - 100000 = 0

Fd = 100,000 lbf

the drag force is 100,000 lbf

b)

as the plane is at constant height

Flift - W = 0

Flift - 500,000 = 0

Flift = 500,000 lbf

the total lift force acting upward on the plane to keep it in the air is 500,000 lbf