Question

An automobile traveling along a straight road

Answer 1

Answer:

t = 2.97[s]

Explanation:

To solve this problem we must use the following kinematics equations, we must bear in mind that the positive sign of the acceleration value means that the car is increased its speed.

$v_{f}^{2} =v_{o}^{2} +(2*a*(x-x_{o} ))$

where:

x - xo = 180 [ft]

a = acceleration [ft/s^2]

Vo = initial velocity = 53 [ft/s]

Vf = final velocity = 68 [ft/s]

Now replacing we find:

(68^2) = (53^2) + (2*a*180)

a = 5.04 [ft/s^2]

Now using the following equation:

$v_{f}=v_{0}+a*t$

68 = 53 + (5.04*t)

t = (68 - 53)/5.04

t = 2.97[s]