The force of the wind blowing on a vertical surface varies jointly as the area of the surface and the square of the velocity. if a wind of 50 mph exerts a force of 20 lb on a surface of 1/5thft2, how much force will a wind of 125 mph place on a surface of 2 ft2?

a force of 1250lb is exerted

Step-by-step explanation:

since the force of the wind varies jointly as the area of the surface and the square of the velocity,

let f = force

a = area

velocity =v

from the above statement, we find out that

----1

that is     -----2

where k is a coefficent of proportionality

since velocity of wind in mph,v =50

and force in lb = 20

and surface area =

from eqn 2

we have that

making k subject of the formula

we have that

that means that  ---3

however, when velocity = 125mph

surface area =

putting values in eqn 3 we have

hence a force of 1250lb is exerted