Glossary
Acceleration
The rate at which an object's velocity changes, which can involve a change in speed, direction, or both.
Example:
When a car speeds up from a stop sign, it experiences positive acceleration.
Acceleration
The rate at which an object's velocity changes over time, including changes in speed or direction.
Example:
A car speeding up on a highway experiences positive acceleration.
Acceleration Due to Gravity (g)
The constant acceleration experienced by any object in free fall near Earth's surface, approximately 10 m/s² downward, regardless of the object's mass.
Example:
When a basketball is thrown into the air, its upward motion slows down and then it falls back to the ground due to the constant 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, illustrating the rate at which its velocity changes.
Example:
If a rocket engine fires, its acceleration vs. time graph would show a constant positive value during the burn, indicating steady thrust.
Acceleration vs. Time Graph
A graph that plots an object's acceleration on the y-axis against time on the x-axis.
Example:
A horizontal line above the x-axis on an acceleration vs. time graph indicates constant positive acceleration.
Area Under the Curve (of a graph)
The region between a graph line and the x-axis, representing the product of the quantities on the y-axis and x-axis over a given interval.
Example:
To find out how far a car traveled, you can calculate the area under the curve of its velocity-time graph.
Area Under the Curve (on motion graphs)
The definite integral of a function between two points on a graph, representing the accumulated change of the y-axis quantity over the x-axis interval.
Example:
The area under the curve of an acceleration vs. time graph gives the change in velocity.
Constant Acceleration
A condition where an object's velocity changes by the same amount in every equal time interval, meaning the rate of change of velocity remains uniform.
Example:
A car steadily increasing its speed on a straight highway, adding 5 m/s to its velocity every second, is experiencing constant acceleration.
Constant Acceleration
A state where an object's velocity changes by the same amount in every equal time interval, meaning the acceleration vector remains unchanged in both magnitude and direction.
Example:
An object in constant acceleration under gravity will increase its speed by approximately 10 m/s every second it falls.
Displacement
The overall change in an object's position from its starting point to its ending point, including both magnitude and direction.
Example:
If a drone flies 100 meters north and then 100 meters south, its total displacement is zero, as it returned to its starting point.
Displacement
The change in an object's position, measured as the straight-line distance and direction from the initial to the final position.
Example:
If you walk 5 meters forward and then 5 meters backward, your total distance is 10 meters, but your displacement is 0 meters.
Final Velocity
The velocity of an object at the end of a specific time interval or motion analysis.
Example:
After a car brakes to a stop, its final velocity is 0 m/s.
Free Fall
The motion of an object solely under the influence of gravity, neglecting air resistance.
Example:
A skydiver before opening their parachute is in free fall.
Gravitational Acceleration (g)
The constant acceleration experienced by objects due to Earth's gravity near its surface, approximately 10 m/s² downwards.
Example:
When you drop a ball, it accelerates downwards at approximately gravitational acceleration (g).
Initial Velocity
The velocity of an object at the beginning of a specific time interval or motion analysis.
Example:
When a rocket launches, its initial velocity is typically 0 m/s.
Instantaneous Acceleration
The acceleration of an object at a specific moment in time, given by the slope of the velocity vs. time graph at that point.
Example:
When you suddenly press the gas pedal, the car experiences a brief burst of instantaneous acceleration.
Instantaneous Velocity
The velocity of an object at a specific moment in time, given by the slope of the position vs. time graph at that point.
Example:
The speedometer in a car shows your instantaneous velocity.
Kinematic Equations
A set of mathematical formulas that describe the motion of objects under constant acceleration, relating displacement, initial velocity, final velocity, acceleration, and time.
Example:
To calculate how long it will take a dropped apple to hit the ground from a certain height, you would use the kinematic equations.
Kinematic Equations
A set of mathematical formulas used to describe the motion of objects with constant acceleration.
Example:
Using the kinematic equations, you can predict how far a ball will travel if you know its initial speed and the time it's in the air.
Motion
The change in an object's position over time.
Example:
A car driving down a straight road exhibits motion.
Motion Diagram
A visual representation showing an object's position at successive, equally spaced time intervals, often with velocity vectors to indicate direction and magnitude.
Example:
A photographer uses a strobe light to capture a series of images of a skateboarder, creating a motion diagram that clearly shows their changing speed and direction.
Position
The location of an object relative to a chosen origin or reference point.
Example:
If you start at the origin, your position after walking 10 meters east is +10 meters.
Position vs. Time Graph
A graph that plots an object's position on the y-axis against time on the x-axis, illustrating its location and movement over a period.
Example:
By looking at a runner's position vs. time graph, you can instantly tell if they were moving forward, backward, or standing still at any given moment.
Position vs. Time Graph
A graph that plots an object's position on the y-axis against time on the x-axis.
Example:
A straight, upward-sloping line on a position vs. time graph indicates constant positive velocity.
Slope (of a graph)
A measure of the steepness of a line on a graph, calculated as the change in the y-axis quantity divided by the change in the x-axis quantity.
Example:
The slope of a position-time graph directly tells you the object's velocity, with a steeper slope indicating a faster speed.
Slope (on motion graphs)
The steepness of a line on a graph, representing the rate of change of the y-axis quantity with respect to the x-axis quantity.
Example:
The slope of a velocity vs. time graph tells you the acceleration.
Time
A scalar quantity representing the duration over which an event or motion occurs.
Example:
It took 5 seconds for the sprinter to run the first 50 meters, so the time interval was 5s.
Total Distance Traveled
The total length of the path an object has moved, regardless of direction, always a positive scalar quantity.
Example:
Even if a robot vacuum ends up back where it started, its total distance traveled would be the sum of all the segments it moved.
Velocity
The rate at which an object changes its position, specified by both its speed and its direction.
Example:
A sailboat moving at 15 km/h eastward has a specific velocity.
Velocity vs. Time Graph
A graph that plots an object's velocity on the y-axis against time on the x-axis, illustrating how its speed and direction change over time.
Example:
The velocity vs. time graph for a car braking to a stop would show a line with a negative slope, starting from a positive velocity and ending at zero.
Velocity vs. Time Graph
A graph that plots an object's velocity on the y-axis against time on the x-axis.
Example:
The area under the curve of a velocity vs. time graph gives the object's displacement.