Unit 4: Acceleration Review

Vocabulary practice flashcards covering Unit 4 acceleration concepts, motion graphs, vector interactions, free fall, and air resistance.

Acceleration

The rate at which an object's velocity is changing over time.

SI Unit of Acceleration

Meters per second squared ($\text{m/s}^2$).

Vector Quantity

A physical measurement, such as velocity or acceleration, that possesses both a magnitude and a direction.

Conditions for Acceleration

Acceleration occurs whenever there is a change in velocity, specifically when an object speeds up, slows down, or changes its direction of motion.

Circular Motion Acceleration

The acceleration an object experiences while moving in a circular path at constant speed because its direction of motion changes continuously at every instant.

Slope of a Velocity vs. Time Graph

The physical property of a velocity-time graph that represents the object's acceleration, measured in units of $\text{m/s}^2$.

Area Under a Velocity vs. Time Graph

The geometric region between the velocity curve and the time axis representing displacement, measured in units of meters ($\text{m}$).

Signed Displacement on a Velocity Graph

Area located above the time axis represents a positive displacement, whereas area located below the time axis represents a negative displacement.

Parallel Acceleration and Velocity

The condition where acceleration points in the same direction as velocity, causing the object to speed up.

Antiparallel Acceleration and Velocity

The condition where acceleration points in the opposite direction of velocity, causing the object to slow down.

Angled Acceleration

The condition where acceleration is directed at an angle relative to the velocity vector, causing the object to turn and change direction.

Free Fall

The motion of a falling object influenced solely by gravity, having an acceleration of $-9.8\,\text{m/s}^2$ (often rounded to $-10\,\text{m/s}^2$).

Acceleration Due to Gravity ($g$)

The magnitude of free-fall acceleration near Earth's surface, designated by the symbol $g$ and valued at approximately $9.8\,\text{m/s}^2$ (rounded to $10\,\text{m/s}^2$).

Mass Independence in Free Fall

The physical principle that an object's mass has no effect on its acceleration during free fall; all objects fall at the identical rate in the absence of air resistance.

Trajectory Peak Velocity

The instantaneous vertical velocity of an object at its maximum height, which is momentarily $0\,\text{m/s}$ as it transitions from moving upward to downward.

Air Resistance

The frictional fluid drag force exerted by air molecules colliding with a moving body, opposing its motion through the atmosphere.

Factors Influencing Air Resistance

The surface area of the moving body (larger area increases drag) and the speed of the body (faster motion increases drag).

Terminal Velocity

The constant maximum speed attained by a falling body when the upward force of air resistance equals the downward gravitational force, causing net acceleration to become zero.

Curved Position vs. Time Graph ($x$ vs. $t$)

Represents motion where an object starts at a positive position, travels in the negative direction (to the left), and slows down as the slope flattens toward zero.

Curved Distance vs. Time Graph (Flattening Slope)

Represents an object that is slowing down over time as the tangent slope of distance versus time decreases.

Curved Distance vs. Time Graph (Steepening Slope)

Represents an object that is accelerating (speeding up over time) as the tangent slope of distance versus time increases.

Position vs. Time Graph (Downward Parabola)

Represents an object starting from rest with zero initial velocity at a positive position and accelerating to the left in the negative direction.

Acceleration Calculation (Figure 6)

An acceleration value of $-2\,\text{m/s}^2$, derived from the slope of the line: $\text{slope} = \frac{0\,\text{m/s} - 10\,\text{m/s}}{5\,\text{s} - 0\,\text{s}} = -2\,\text{m/s}^2$.

Acceleration Calculation (Figure 7)

An acceleration value of $2\,\text{m/s}^2$, derived from the slope of the line: $\text{slope} = \frac{5\,\text{m/s} - (-3\,\text{m/s})}{4\,\text{s} - 0\,\text{s}} = \frac{8\,\text{m/s}}{4\,\text{s}} = 2\,\text{m/s}^2$.