KE = ½ * 5 * 10^6 * 0.0188^2
½ * 3000 * v^2 = ½ * 5 * 10^6 * 0.0188^2
Solve for v
3000 * v^2 = 5 * 10^6 * 0.0188^2
v = 0.768 m/s
You solved for acceleration, assuming that the force was constant.
Let’s use average force to determine the average acceleration!
Average force = mass * average acceleration
½ * 5 * 10^6 * 0.0188 = 3000 * average acceleration
average acceleration = 15.67 m/s^2
The average force caused the velocity to decrease to 0 m/s as the car moved 0.0188 meter.
So the acceleration is negative. (-15.67 m/s^2)
The following equation is useful, when you have acceleration and distance, but do not know the elapsed time.
vf^2 - vi^2 + (2 * a *d)
vf = 0
d = 0.0188
a = -15.67
0 – vi^2 = 2 * -15.67 * 0.0188
vi =(2 * -15.67 * 0.0188)^0.5 = 0.767 m/s^2
You can get the correct answer if you use the average acceleration!!
Force * time = mass * change of velocity
Not F * distance = mass * change of velocity
I hope this helps you!!