Question

if a speeding train hits the brakes and it takes the train 45 seconds to go from 40.9 mph to 11.7 mph what is the acceleration? answer: box check what are the units for your answer to question 13? select one: seconds, mph, mph/s, miles your answer is correct.

Explanation:

Step1: Recall acceleration formula

Acceleration \( a = \frac{\Delta v}{\Delta t} \), where \( \Delta v = v_f - v_i \), \( v_f = 11.7 \) mph, \( v_i = 40.9 \) mph, \( \Delta t = 45 \) s.

Step2: Calculate velocity change

\( \Delta v = 11.7 - 40.9 = -29.2 \) mph.

Step3: Compute acceleration

\( a = \frac{-29.2}{45} \approx -0.649 \) mph/s.

Answer:

\( \approx -0.65 \) mph/s (or exact value \( \frac{-29.2}{45} \) mph/s)