Final answer:
The applied force needed to accelerate a 12 kg lawnmower from rest to 1.25 m/s in 3 seconds is 5 N, which is not listed in the provided options. The closest provided answer choice is 4 N.
Step-by-step explanation:
To find the magnitude of the applied force required to accelerate a 12 kg lawnmower from rest to 1.25 m/s in 3 s, we use Newton's second law of motion, which states that Force (F) = mass (m) × acceleration (a). First, we must calculate the acceleration using the formula a = (Δv) / t, where Δv is the change in velocity and t is the time taken. Since the lawnmower starts from rest, its initial velocity is 0 m/s, and its final velocity is 1.25 m/s, so the change in velocity (Δv) is 1.25 m/s. Given the time (t) is 3 s, the acceleration (a) can be calculated as a = 1.25 m/s / 3 s = 0.4167 m/s².
Now, applying Newton's second law, the force to accelerate the lawnmower can be calculated as F = m × a = 12 kg × 0.4167 m/s² = 5 N. However, this value does not match any of the options provided in the question. It's possible there might be a mistake in the question choices or the setup; the closest value to our calculation is 4 N (option a), but the exact answer is not listed. It is important to confirm the details of the question and the available answers.