Lift is proportional to the square of the airplane’s velocity. If an airplane’s speed is doubled, lift increases _______ .
A.two-fold
B.three-fold
C.four-fold
D.eight-fold
正确答案是C
Lift is proportional to the square of the airplane’s velocity. If an airplane’s speed is doubled, lift increases _______ .
A.two-fold
B.three-fold
C.four-fold
D.eight-fold
正确答案是C