Question at position 43 Newton’s Second Law of Motion tells us that the net force applied to an object equals its _________mass multiplied by its energy.mass multiplied by its velocity.mass multiplied by its acceleration.acceleration divided by its mass.momentum multiplied by its velocity.Clear my selection

Question

BlackTom AI · Accepted Answer

Newton’s Second Law is commonly written as F = ma, meaning net force equals mass multiplied by acceleration.

1. Relevant knowledge points and concepts
- Force (F) is a vector quantity measured in newtons (N). 
- Mass (m) is measured in kilograms (kg). 
- Acceleration (a) is change in velocity per time, measured in meters per second squared (m/s^2). 
- The law can be derived from momentum p = mv: F = dp/dt. For constant mass, dp/dt = m dv/dt = ma, so F = ma.

2. Step-by-step reasoning process
- Start from F = dp/dt. If mass is constant, p = mv, so dp/dt = m(dv/dt) = ma.
- Therefore net force is mass times acceleration; this is the direct statement of Newton’s Second Law.

3. Calculations and intermediate steps (example)
- Suppose m = 2 kg and acceleration a = 3 m/s^2.
- Compute F = m × a = 2 kg × 3 m/s^2 = 6 kg·m/s^2 = 6 N.
- Units check: kg·m/s^2 is the unit of force (newton), consistent with F = ma.

4. Why the correct answer is correct
- "Mass multiplied by its acceleration" matches F = ma both algebraically and dimensionally, and follows from F = dp/dt for constant mass. It gives the correct physical relationship between force, mass, and acceleration.

5. Why the other options are incorrect
- "Mass multiplied by its energy": Multiplying mass by energy has units of kg·J and no physical law states force equals mass times energy. Units and concepts mismatch.
- "Mass multiplied by its velocity": m·v is momentum (kg·m/s), not force. Force is the rate of change of momentum, not momentum itself.
- "Acceleration divided by its mass": a/m has units of (m/s^2)/kg and does not represent force; incorrect inversion of the correct relation.
- "Momentum multiplied by its velocity": p·v = (mv)·v = m v^2 (units kg·m^2/s^2), which has units of energy, not force; no law equates this product to net force.

6. Conclusion
The correct statement of Newton’s Second Law is that net force equals mass multiplied by acceleration; this matches the provided answer: "mass multiplied by its acceleration."

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