Final answer:
The force applied to accelerate a 3kg object to 10 m/s over 2 seconds is calculated using Newton's second law (F = ma), resulting in a force of 15 N.
Step-by-step explanation:
To calculate the force applied to the 3kg object that is sped up to 10 m/s over 2 seconds, you can use Newton's second law of motion, which states that force equals mass times acceleration (F = ma). First, determine the acceleration (a) by using the formula a = Δv/Δt, where Δv is the change in velocity and Δt is the time period over which the change occurs. Since the object starts from rest, its initial velocity is 0 m/s, and it accelerates to 10 m/s in 2 seconds, therefore a = (10 m/s - 0 m/s) / 2 s = 5 m/s². Now apply the equation F = ma, with m being the mass (3 kg) and a being the acceleration (5 m/s²), so the force applied is F = 3 kg × 5 m/s² = 5 N. Hence, the correct answer is D. 5 N.