Newton’s First Law: Inertia, Reference Frames, and Equilibrium

All flashcards

What is Newton’s first law?

An object remains at rest or moves at constant velocity unless a net external force acts on it.

What is inertia?

An object’s resistance to changes in its velocity, whether it is at rest or moving.

How is mass related to inertia?

Mass measures an object’s inertia; greater mass means greater resistance to a change in motion.

What is an inertial reference frame?

A frame in which an object with zero net force has constant velocity.

What distinguishes static from dynamic equilibrium?

Static equilibrium is rest with balanced forces; dynamic equilibrium is constant-velocity motion with balanced forces.

Quiz questions

1. What defines an inertial reference frame?Answer: A frame where zero net force corresponds to constant velocity.
2. A car moves at constant velocity while its forces balance. What kind of equilibrium describes its motion?Answer: Dynamic equilibrium.
3. What does a zero net force tell you about the individual forces acting on an object?Answer: Individual forces may act, but their vector sum is zero.
4. A resultant force is $30\,\hat{i} + 40\,\hat{j}\,\text{N}$. Which force would balance it?Answer: $-30\,\hat{i} - 40\,\hat{j}\,\text{N}$
5. What does an object’s weight describe?Answer: The magnitude of the gravitational force acting on the object.