Question

If P is the force acting on the body, m is the mass of the body and a is the acceleration of the body, then according to Newton's second law of motion: ____.

• A. P + m.a = 0
• B. P - m.a = 0
• C. P × m.a = 0
• D. P m.a = 0

Hint:

Think of $P = ma$ as the "active" form of the law and $P - ma = 0$ as the "equilibrium" form. Both describe the same physical reality: force and mass-acceleration are always perfectly balanced.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Newton's Second Law defines the relationship between force, mass, and acceleration, stating that the force applied to an object is equal to the rate of change of its momentum.

Step 2: Key Formula or Approach:
The standard mathematical form is: \[ P = m \cdot a \]

Step 3: Detailed Explanation:
The law states that the net force ($P$) acting on a body is the product of its mass ($m$) and its acceleration ($a$). To express this as an equation equal to zero (often used in D'Alembert's principle where $-ma$ is considered an inertial force): \[ P = m \cdot a \] Subtracting $m \cdot a$ from both sides: \[ P - m \cdot a = 0 \] This shows the balance between the applied force and the inertial resistance of the body.

Step 4: Final Answer:
According to the law, the correct relation is P - m.a = 0.