Glossary
Acceleration
The rate at which an object's velocity changes over time, which can involve a change in speed, direction, or both.
Example:
When a roller coaster speeds up as it plunges down a hill, it experiences significant positive Acceleration.
Acceleration due to Gravity (g)
The constant acceleration experienced by objects in free fall near the Earth's surface, approximately 9.8 m/s² (often rounded to 10 m/s² for AP Physics 1 calculations).
Example:
When you drop a ball, it speeds up at a rate of 9.8 m/s every second due to the Acceleration due to Gravity.
Acceleration vs. Time Graph
A graph that plots an object's acceleration on the y-axis against time on the x-axis. The area under the curve represents the change in velocity.
Example:
If a rocket's Acceleration vs. Time Graph shows a constant positive value, it means its velocity is increasing steadily.
Analytical Representations
Describing motion using mathematical equations, which are useful for making predictions and solving problems.
Example:
Using the equation is an Analytical Representation to predict a rocket's position.
Angled Launches
Projectile motion where an object is launched with an initial velocity that has both horizontal and vertical components, typically at an angle to the horizontal.
Example:
Kicking a soccer ball high into the air involves Angled Launches, as the initial force sends it both forward and upward.
Area (under a graph)
The region enclosed between the curve of a graph and the x-axis, which often represents the accumulated quantity of the y-axis variable.
Example:
The Area under a velocity-time graph tells you the total displacement of an object.
Center of Mass
The unique point where the weighted average of all the mass of a system is located; it's the point where a force can cause linear acceleration without rotation.
Example:
When a gymnast performs a flip, their body rotates around their Center of Mass, which might even be outside their body during certain poses.
Diagrammatic Representations
Visualizing motion through sketches, diagrams, or free-body diagrams to understand the physical situation.
Example:
Drawing a simple sketch of a ball rolling down a ramp is a Diagrammatic Representation that helps visualize its path.
Displacement
The overall change in an object's position, measured as the straight-line distance and direction from its starting point to its ending point.
Example:
If you walk 5 meters east and then 5 meters west, your total Displacement is zero, even though you walked 10 meters.
Free Fall
The motion of an object solely under the influence of gravity, neglecting air resistance.
Example:
A skydiver just after jumping from a plane, before opening their parachute, is in Free Fall.
Graphical Representations
Methods of displaying motion using graphs, such as position-time, velocity-time, and acceleration-time graphs, to visualize relationships between variables.
Example:
Analyzing a car's journey by plotting its speed over time on a Graphical Representation helps identify when it was accelerating or decelerating.
Horizontal Motion (Projectile)
The component of a projectile's motion that occurs along the x-axis, characterized by constant velocity (assuming no air resistance).
Example:
In Horizontal Motion, a ball rolling off a table continues to move forward at a steady speed as it falls.
Kinematics Equations (Big Four)
A set of four fundamental equations that describe the motion of objects with constant acceleration, relating displacement, initial velocity, final velocity, acceleration, and time.
Example:
When a car accelerates uniformly, you can use the Kinematics Equations to calculate how far it travels or how long it takes to reach a certain speed.
Linear Function
A mathematical relationship that, when graphed, produces a straight line, typically represented by the equation y = mx + b.
Example:
The relationship between the distance traveled by a car at constant speed and time is a Linear Function.
Linearization
A technique used to transform a nonlinear relationship into a linear one by manipulating the variables (e.g., squaring one axis) to make data analysis easier.
Example:
To analyze the relationship between position and time for an accelerating object, you might use Linearization by plotting position versus time squared to get a straight line.
Nonlinear Function
A mathematical relationship that, when graphed, produces a curved line, indicating a non-constant rate of change.
Example:
The path of a thrown baseball is described by a Nonlinear Function due to gravity.
Numerical Representations
Representing motion using tables or lists of data points, showing specific values of position, velocity, or acceleration at different moments.
Example:
A scientist might use a Numerical Representation to record the exact height of a bouncing ball at one-tenth of a second intervals.
Parabola (Projectile Path)
The characteristic curved, symmetrical path that a projectile follows when launched into the air, assuming negligible air resistance.
Example:
The trajectory of a water stream from a garden hose forms a perfect Parabola.
Position vs. Time Graph
A graph that plots an object's position on the y-axis against time on the x-axis. Its slope represents the object's velocity.
Example:
If a runner's Position vs. Time Graph shows a straight, upward-sloping line, it means they are moving at a constant positive velocity.
Projectile Motion
The two-dimensional motion of an object launched into the air, where the only significant force acting on it after launch is gravity.
Example:
The arc of a basketball shot is a classic example of Projectile Motion.
Slope (of a graph)
The steepness of a line on a graph, calculated as 'rise over run,' which indicates the rate of change between the variables plotted.
Example:
On a distance-time graph, a steeper Slope means the object is moving faster.
Tangent Line
A straight line that touches a curve at a single point and has the same slope as the curve at that specific point.
Example:
To find the instantaneous velocity from a curved position-time graph, you can draw a Tangent Line at the point of interest and calculate its slope.
Vector Components
The perpendicular parts (typically horizontal and vertical) that combine to form a single vector, allowing for easier analysis of motion in two dimensions.
Example:
To analyze a force applied at an angle, you break it down into its Vector Components – how much force is pushing horizontally and how much is pushing vertically.
Velocity
The rate at which an object changes its position, including both its speed and its direction.
Example:
A car traveling at 60 mph north has a different Velocity than a car traveling at 60 mph south, even though their speeds are the same.
Velocity vs. Time Graph
A graph that plots an object's velocity on the y-axis against time on the x-axis. Its slope represents acceleration, and the area under the curve represents displacement.
Example:
A car's Velocity vs. Time Graph showing a horizontal line above the x-axis indicates constant speed, while a sloped line indicates acceleration.
Vertical Motion (Projectile)
The component of a projectile's motion that occurs along the y-axis, characterized by constant downward acceleration due to gravity.
Example:
The upward and downward movement of a thrown ball is its Vertical Motion, constantly affected by gravity.