# The lift ( L ) experienced by the plane travelling at 40 mi / h with wing area of 600 ft 2 .

### Precalculus: Mathematics for Calcu...

6th Edition
Stewart + 5 others
Publisher: Cengage Learning
ISBN: 9780840068071

### Precalculus: Mathematics for Calcu...

6th Edition
Stewart + 5 others
Publisher: Cengage Learning
ISBN: 9780840068071

#### Solutions

Chapter 1.11, Problem 38E
To determine

## To find: The lift (L) experienced by the plane travelling at 40 mi/h with wing area of 600 ft2 .

Expert Solution

The lift (L) experienced by the plane is 1305.6lb .

### Explanation of Solution

Given:

Lift (L) is jointly proportional to square of speed (s) of plane and area of its wing.

Lift experienced is 1700lb if plane travels at 50mi/h with wing area of 500ft2 .

Calculation:

The given variation is, lift (L) is jointly proportional to square of speed (s) of plane and area (A) of its wing.

Mathematically,

L=kAs2 (1)

Here, k is constant of proportionality.

First calculate constant of proportionality.

Substitute 1700 for L , 500 for A and 50 for s in equation (1) and solve for k .

1700=k(500)(502)1700=k(500)(2500)1700=k(1250000)17001250000=k

Simplify the above equation and get the value of k .

k=0.00136 (2)

Now use the value of k and find lift for given speed and wing area.

Substitute 40 for s , 600 for A and 0.00136 from equation (2) in equation (1).

L=0.00136(600)(402)L=0.00136(600)(1600)L=1305.6

Thus, the value of lift experienced by the plane is 1305.6lb .

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