Chapter 3 – Forces Flashcards

A set of vocabulary flashcards based on the Chapter 3 forces lecture, covering definitions, units, and the three laws of motion.

Force

A push or a pull.

Vector

A quantity that has both magnitude (size) and direction.

Scalar

A quantity that has magnitude (size) only.

Newton (N)

The unit in which force is measured.

Spring balance

An instrument used to measure force, also known as a Newton meter.

Contact force

A force that can only be applied on an object if it is in contact with (touching) that object.

Non-contact force

A field force that does not have to touch an object in order to apply a force, resulting from action-at-a-distance.

Force field

A region around an object in which another object will experience a force.

Mass

The amount of matter an object consists of, measured in kilograms ($kg$).

Weight

The gravitational force the Earth exerts on any object on or near its surface, measured in Newtons ($N$).

Gravitational field strength ($g$)

A value representing the strength of the gravitational field around a planet; for Earth it is approximately $9,8\,N/kg$ (or $m/s^2$).

Normal force ($F_N$)

The perpendicular force exerted by a surface on an object in contact with it.

Frictional force ($F_f$)

The force that opposes the motion of an object and acts parallel to the surface with which the object is in contact.

Static friction

The friction that exists between two surfaces that are not moving relative to each other.

Kinetic friction

The friction that exists between two surfaces that are moving relative to each other, also called sliding friction.

Net (Resultant) force ($F_{net}$)

The single force that has the same effect as all the other forces acting together.

Inertia

The property of matter that causes it to resist a change in its state of rest or constant motion; it is directly related to the mass of an object.

Newton’s First Law of Motion

An object continues in a state of rest or uniform velocity unless it is acted upon by a net or resultant force.

Equilibrium

A state where a system of forces is balanced, resulting in a net force of $0\,N$ and zero acceleration.

Newton’s Second Law of Motion

When a net force is applied to an object of mass $m$, it accelerates in the direction of the net force; the acceleration is directly proportional to the net force and inversely proportional to the mass ($F_{net} = ma$).

Newton’s Third Law of Motion

If object A exerts a force on object B, then at the same time object B exerts an oppositely directed force of equal magnitude on object A.