Forces, Energy, and Motion Flashcards

Comprehensive vocabulary flashcards covering motion, forces, Newton's three laws of motion, motion graph interpretation, First Nations technologies, and measurement concepts from the lecture series.

Scalar quantity

A physical quantity that is completely described by size (magnitude) only, such as distance or speed.

Vector quantity

A physical quantity described by both size (magnitude) and direction, such as displacement, velocity, force, or acceleration.

Distance

The total length of a given path travelled between two points, which is a scalar quantity.

Displacement

The straight-line distance and direction between the start and finish of a motion, regardless of the path taken, which is a vector quantity.

Speed

The rate of change of distance over time, calculated using the formula $\text{speed} = \frac{\text{distance}}{\text{time}}$.

Average Speed ($v_{\text{av}}$)

The total distance travelled divided by the total time taken, expressed in symbols as $v_{\text{av}} = \frac{d}{t}$.

Velocity ($v$)

The rate of change of displacement over time ($v = \frac{\Delta x}{t}$), which is a vector quantity that must always specify direction.

Acceleration ($a$)

The rate of change in velocity over time ($a = \frac{v - u}{t}$), usually measured in $m/s^2$, caused by unbalanced forces acting on an object.

Deceleration

A specific term for negative acceleration that refers to an object slowing down.

Applied force

A push or pull exerted on an object by another object or person.

Net force

The overall or resultant force acting on an object after direction is considered; a non-zero net force causes a change in motion.

Newton's First Law of Motion

States that an object will maintain a constant velocity (at rest or moving in a straight line) unless acted upon by an unbalanced force; also known as the law of inertia.

Inertia

The property of matter by which an object continues in its existing state of rest or uniform motion unless acted on by an external force.

Normal reaction force

An upward force acting at right angles ($90^\circ$) to a surface that balances the downward weight of an object.

Newton's Second Law of Motion

States that an object's acceleration depends on the net force acting on it and its mass, calculated as $F_{\text{net}} = m \times a$.

Force equation triangle

A visual tool displaying the algebraic relationships between net force ($F_{\text{net}}$), mass ($m$), and acceleration ($a$), where $F_{\text{net}} = ma$, $a = \frac{F_{\text{net}}}{m}$, and $m = \frac{F_{\text{net}}}{a}$.

Mass

The amount of matter in an object, typically measured in kilograms ($kg$), which remains constant regardless of location or gravitational field strength.

Weight ($W$)

The gravitational force exerted on an object with mass ($W = mg$), measured in newtons ($N$), which varies depending on gravitational field strength.

Gravitational field strength ($g$)

The force exerted by gravity per unit mass, equal to $9.8\,N/kg$ on Earth's surface, $1.6\,N/kg$ on the Moon, $3.7\,N/kg$ on Mercury, and $25\,N/kg$ on Jupiter.

Newton's Third Law of Motion

States that whenever one object exerts a force on a second object, the second object exerts an equal and opposite force back on the first.

Free-body diagram

A diagram used to illustrate the relative magnitude and direction of all forces acting upon an object in a given situation.

Third-class lever

A lever system where the effort force is applied in between the fulcrum and the load, as seen in the human arm or a spear-thrower.

Spear-thrower

A wooden tool used by First Nations peoples that acts as a third-class lever to extend the thrower's arm, increasing the contact time of force application to achieve higher final spear velocity.

Doppler effect

The change in frequency of reflected laser or radar waves from a moving vehicle, used by speed cameras to calculate vehicular speed.

Displacement-time graph

A graph showing displacement on the vertical axis against time on the horizontal axis; its gradient represents velocity, and a flat line indicates the object is stationary.

Velocity-time graph

A graph showing velocity on the vertical axis against time on the horizontal axis; its gradient represents acceleration, a flat line represents constant velocity, and the area underneath represents displacement.

Reaction distance

The distance a vehicle travels while the driver processes a hazard and applies the brakes during their reaction time.

Braking distance

The distance a vehicle travels while decelerating after the brakes have been engaged.

Accelerometer

A tiny sensor embedded in electronic devices like smartphones and smartwatches to measure acceleration and track physical movement.