A car is traveling at 26.0 m/s when the driver suddenly applies the brakes, causing the car to slow down with constant acceleration. The car comes to a stop in a distance of 120 m. How fast was the car moving when it was 60.0 m past the point where the brakes were applied?
A) 22.5 m/s
B) 12.1 m/s
C) 15.0 m/s
D) 18.4 m/s
E) 9.20 m/s

Question

A car is traveling at  26.0 m/s when the driver suddenly applies the brakes, causing the car to slow down with constant acceleration. The car comes to a stop in a distance of  120 m. How fast was the car moving when it was  60.0 m  past the point where the brakes were applied?
A)  22.5 m/s
B)  12.1 m/s
C)  15.0 m/s
D)  18.4 m/s
E)  9.20 m/s

Quizplus · Accepted Answer

To find the speed of the car after it has traveled 60.0 m, we can use the equation derived from the kinematic equations for constant acceleration, $v^2 = u^2 + 2as$, where $v$ is the final velocity, $u$ is the initial velocity, $a$ is the acceleration, and $s$ is the distance. Since the car comes to a stop, $v = 0$ when $s = 120$ m. Rearranging the equation to solve for $a$, we get $a = -\frac{u^2}{2s}$. Plugging in the values, $a = -\frac{(26.0)^2}{2(120)}$. Then, to find the speed at 60.0 m, we use the same equation with $s = 60.0$ m and solve for $v$, resulting in $v = \sqrt{u^2 + 2as}$. Substituting the calculated acceleration and the given values, we find that $v$ is approximately 18.4 m/s.

A Car Is Traveling at 26