An initially motionless test car is accelerated uniformly to 145 km/h in 7.88 se
ID: 1519001 • Letter: A
Question
An initially motionless test car is accelerated uniformly to 145 km/h in 7.88 seconds before striking a simulated deer. The car is in contact with the faux fawn for 0.395 seconds, after which the car is measured to be traveling at 82.0 km/h. What is the magnitude of the acceleration of the car before the collision? What is the magnitude of the average acceleration of the car during the collision? What is the magnitude of the average acceleration of the car during the entire test, from when the car first begins moving until the collision is over?Explanation / Answer
Vi = initial velocity of car = 0 m/s
Vf = final velocity of car = 145 km/h = 40.3 m/s
t = time = 7.88 s
acceleration is given as
a = (Vf - Vi) / t = (40.3 - 0) / 7.88 = 5.11m/s2
During collision
Vi = initial velocity of car = 40.3 m/s
Vf = final velocity of car = 82 km/h = 22.8 m/s
t = time = 0.395 s
acceleration is given as
a = (Vf - Vi) / t = (22.8 - 40.3) / (0.395) = - 44.3 m/s2
for average acceleration :
Vi = initial velocity of car = 0 m/s
Vf = final velocity of car = 82 km/h = 22.8 m/s
t = time = 7.88 + 0.395 s
acceleration is given as
a = (Vf - Vi) / t = (22.8 - 0) / (7.88 + 0.395) = 2.76 m/s2