Question

show work and label properly with right units. please highlight bpth answers.

1. A car drives west on 8th street at 32.9 mph. The driver hits the brakes and the car slows down with a constant accelaration of 4.29 m/s^2. How long (time) does it take the car come to a complete stop?

2.Aircraft landing on the uss George h.w. Bush slowed down by arresting wires from a speed of 150 mph to a stop in less than 400feet. What is the magnitude of the average accelaration the aircraft and, thus, the pilots experience?

Answer 1

appply the kinematic equation V = u + at

where u is initail velocity = 32.9 mph

1mph = 0.4470 m/s

so u = 32.9 * 0.4470 = 14.7 m/s

a is accleration = -4.29 m/s^2

t is time = ?

as it stops , V = 0

so u = -at

t = 14.7 /-(-4.29)

t = 3.428 secs ---------------<<<<<<<<<<<<<<<<Answert to part A

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again use the kinemtic eqn v^2 - u^2 = 2aS

here S = 400 ft = 400 * 0.3048 = 121.92 m

u = 150 mph = 150* 0.4470 = 67.05 m/s

so

accleration a = v^2/2S = 67.05*67.05/(2* 121.92)

a = 18.43 m/s^2 ---------------------<<<<<<<<<<<<<<<<Answer to part B