Final answer:
The deceleration experienced by Dale Earnhardt Jr. after hitting the wall at 120 mph is approximately -13.55 m/s². This calculation uses the conversion of speed to meters per second and time to seconds, and applies the formula for deceleration.
Step-by-step explanation:
The student is interested in calculating the deceleration that Dale Earnhardt Jr. experienced after hitting the wall at a speed of 120 mph.
First, we convert 120 mph to meters per second to match the SI units of deceleration: 120 mph = 53.6448 m/s. The time given is .0011 hours, which we convert to seconds: .0011 hours = 3.96 seconds.
Now, we use the formula for deceleration, which is the change in velocity divided by the time taken. Since the final velocity is 0 m/s after hitting the wall, the change in velocity is 53.6448 m/s. Using the formula deceleration = (final velocity - initial velocity) / time, we get:
deceleration = (0 m/s - 53.6448 m/s) / 3.96 s
The deceleration is approximately -13.55 m/s². The negative sign indicates that it's a reduction in speed, consistent with the concept of deceleration.