Final answer:
Without knowing the time it took for the car to accelerate from 40 m/s to 70 m/s, we cannot calculate the average acceleration; hence, the question cannot be answered with the provided choices.
Step-by-step explanation:
To determine the average acceleration of a car that speeds up from 40 m/s to 70 m/s, you would use the formula for acceleration, which is:
acceleration = (final velocity - initial velocity) / time
However, since the time it takes for this change in velocity is not provided, we cannot calculate the exact acceleration. Generally, you would need to know the time period over which the change in speed took place to calculate the acceleration. Without this information, none of the answer choices A) 10 m/s², B) 20 m/s², C) 30 m/s², or D) 5 m/s² can be confirmed as correct. For example, if given 10 seconds for the time, the acceleration would be (70 m/s - 40 m/s) / 10 s = 3 m/s², which is not an option provided. Therefore, additional information is needed to answer the question.