Final answer:
Using the formula Vf = a × t with the acceleration due to gravity at 9.8 m/s², the final velocity of an object dropped for 3 seconds is 29.4 m/s, so the answer is B. Vf = 29.4 m/s.
Step-by-step explanation:
The velocity of an object when hitting the ground after being dropped for 3 seconds can be calculated using the formula Vf = a × t. Assuming the object is dropped in a vacuum where air resistance is negligible and the acceleration due to gravity (a) is 9.8 m/s², the final velocity (Vf) can be found by multiplying the acceleration due to gravity by the time it was falling.
So, Vf = 9.8 m/s² × 3 s = 29.4 m/s. Therefore, the correct answer is B. Vf = 29.4 m/s.