Ajet plane lands with a speed of 87 m/s and can accelerate at a maximum rate of −4.10 m/s2 as it comes to rest. (a) from the instant the plane touches the runway, what is the minimum time needed before it can come to rest?

21.22s

Explanation:

initial velocity u=87m/s

acceleration a=-4.10 m/s²

velocity v=0

time t=?

From Newton's first law of motion

V=u+at

0=87-4.10t

-87=-4.1t

t= -87/-4.1

t= 21.22 s

when the velocity of a mass on a spring is zero, the acceleration is at a maximum .