How Forces Affect Motion

Vocabulary flashcards covering the key terms, laws, and concepts from Chapter 6: How Forces Affect Motion.

Force

A physical quantity requiring magnitude, unit, and direction that can cause an object to move from rest, change its speed or direction of motion, or alter its shape.

newton

The SI unit of force (symbolized as $N$), defined as the force that produces an acceleration of $1\,m\,s^{-2}$ on an object of mass $1\,kg$.

Balanced Forces

Two forces acting on an object that are equal in magnitude but opposite in direction, resulting in a net force of zero and no change in motion.

Unbalanced Forces

Forces acting on an object that are not equal in magnitude or not opposite in direction, producing a non-zero net force that changes the object's motion.

Force of Friction

A force arising between contacting surfaces that acts in a direction opposite to the direction of motion or applied force.

Normal Force

The force exerted by a surface on an object placed on it, acting in an upward direction perpendicular to the surface.

Thought Experiment

An experiment carried out in the mind when the physical conditions required for the experiment (such as a completely frictionless surface) are difficult to recreate in the real world.

Galileo Galilei

The 17th-century scientist who argued through thought experiments that if a body moves along a horizontal plane and all impediments are removed, it will continue to move indefinitely.

Isaac Newton

The scientist who used the word 'inertia' to describe the resistance of objects to changes in motion, framed three laws of motion in 1687, and after whom the unit of force is named.

Inertia

The inherent tendency of objects to resist any change in their state of rest or uniform motion.

Newton's First Law of Motion

The law stating that an object at rest remains at rest, and an object in motion continues to move with a constant velocity, unless acted upon by a net force.

Newton's Second Law of Motion

The law stating that when a net force acts on an object, the object accelerates in the direction of the net force with an acceleration proportional to the net force and inversely proportional to its mass ($F = ma$).

Momentum

A physical quantity defined as the product of an object's mass and velocity, pointing in the same direction as its velocity.

Acceleration Due to Gravity ($g$)

The acceleration experienced by an object falling towards Earth under gravitational force, equal to approximately $9.8\,m\,s^{-2}$ near Earth's surface.

Newton's Third Law of Motion

The law stating that whenever one object exerts a force on a second object, the second object simultaneously exerts an equal and opposite force on the first object.

Millinewton

A unit of force equal to $10^{-3}\,N$, representing the order of magnitude of the smallest forces directly feelable in everyday human life.

Yoctonewton

A unit of force equal to $10^{-24}\,N$, representing the order of extremely small forces measurable by scientists in specialized experiments.

System of Objects

A collection of connected objects treated as a single entity, where internal forces between objects cancel out and overall acceleration depends on net external forces.