Question

With good tires and breaks, a car traveling 50 mi/hr on dry pavement can travel 400 ft when the driver reacts to something he sees and brings the vehicle to a stop. If this is done uniformly, what is the car's acceleration?

Answer 1

Answer:$6.72 m/s^2$

Explanation:

Given

initial velocity $u=50 mi/hr\approx 73.33 ft/s$

Distance traveled before stopping $s=400 ft$

using equation of

$v^2-u^2=2as$

where v=final velocity

u=initial Velocity

a=acceleration

s=displacement

v=0 as car stops after travelling $400 ft$

$0-73.33^2=2\times a\times 400$

$a=-6.72 m/s^2$

negative sign indicates it is deceleration