Final answer:
The acceleration of the rock is calculated by subtracting initial velocity from final velocity to get the change in velocity, then dividing by the time interval. After performing the calculations, the correct answer is 0.15 mph/s.
Step-by-step explanation:
The acceleration of the rock as it rolls down the hill can be calculated using the formula acceleration (a) = Δvelocity / Δtime. To find this, we subtract the initial velocity from the final velocity and then divide by the time taken to change speed. The rock starts at 10 mph and speeds up to 25 mph over a period of 10 seconds, so Δvelocity is 25 mph - 10 mph = 15 mph. We convert mph to mph/s by dividing by 3600 (the number of seconds in an hour), so 15 mph is equivalent to 15/3600 mph/s. We then divide this by the time interval of 10 seconds:
Δvelocity = 25 mph - 10 mph = 15 mph
a = Δvelocity / Δtime = (15/3600) mph/s / 10 s
After calculating, we find that the acceleration is 0.15 mph/s (Option A).