Final answer:
The average velocity for an object with constant acceleration is the arithmetic mean of the initial and final velocities. For a car accelerating from 7.8 m/s to 11.4 m/s, the average velocity is calculated to be 9.6 m/s, answer A.
Step-by-step explanation:
The average velocity of a car that accelerates from 7.8 m/s to 11.4 m/s, assuming constant acceleration, can be calculated by taking the arithmetic mean of the initial and final velocities. The formula to find average velocity (vavg) with constant acceleration is:
vavg = (vi + vf) / 2
Where vi is the initial velocity and vf is the final velocity. Plugging in our values, we get:
vavg = (7.8 m/s + 11.4 m/s) / 2 = 19.2 m/s / 2 = 9.6 m/s
Therefore, the correct answer is A) 9.6 m/s.