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Difficulty: MediumMechanics and Motion

In classical mechanics, fundamental laws and principles define how forces govern the motion and interaction of physical bodies. Match each mechanical principle with its correct scientific definition or governing rule.

  • Newton's First Law of MotionAn object at rest remains at rest, and an object in motion continues at a constant velocity along a straight line unless acted upon by a net external force.
  • Newton's Second Law of MotionThe acceleration produced on a body is directly proportional to the net force applied to it and inversely proportional to the mass of the body (Fnet=maF_{\text{net}} = ma).
  • Newton's Third Law of MotionWhen two distinct bodies interact, the force exerted by the first body is equal in magnitude and opposite in direction to the force exerted by the second body.
  • Law of Conservation of MomentumThe total vector sum of mass multiplied by velocity for all objects in a closed system remains constant when no net external force acts on the system.

Answer

Newton's First Law pairs with the statement describing an object maintaining constant velocity unless acted upon by a net force; Newton's Second Law pairs with the statement that acceleration is directly proportional to net force and inversely proportional to mass; Newton's Third Law pairs with the statement regarding equal and opposite force interactions between two bodies; and the Law of Conservation of Momentum pairs with the statement that total mass times velocity remains constant in a closed system.
Each mechanical principle aligns directly with its formal physical definition: Newton's First Law governs inertia and zero-acceleration states; Newton's Second Law defines how net force produces acceleration proportional to force and inversely proportional to mass; Newton's Third Law defines equal and opposite force pairs between interacting bodies; and the Law of Conservation of Momentum dictates the invariance of total system momentum in closed systems.

Step-by-Step Solution

1
Identify the foundational definition of inertia and unaccelerated motion.
Newton's First Law matches the description of objects maintaining rest or uniform straight-line motion unless a net external force intervenes.
Inertia requires zero net force for constant velocity.
2
Identify the quantitative relationship governing net force, acceleration, and mass.
Newton's Second Law matches the relationship where acceleration is proportional to net force and inversely proportional to mass (Fnet=maF_{\text{net}} = ma).
This law provides the direct causal formula for changing an object's velocity.
3
Identify the law governing reciprocal force pairs between interacting objects.
Newton's Third Law matches the statement of equal and opposite forces acting simultaneously on two separate bodies.
Forces in nature always exist in matched action-reaction pairs across interacting bodies.
4
Identify the principle governing total quantity of motion across collisions in isolated systems.
The Law of Conservation of Momentum matches the constant total vector product of mass and velocity (mvmv) in closed systems.
Internal interaction forces cancel out vectorially across the entire system, preserving total momentum.

Key Concept

Fundamental Principles and Governing Laws of Classical Mechanics
Estimated Time:1m 0s
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Topics

Mechanics and Motion

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