Glossary
Acceleration
The rate of change of an object's velocity, which can involve a change in speed, direction, or both.
Example:
When a roller coaster speeds up as it goes down a hill, it experiences positive acceleration.
Direction
The orientation or path along which a vector quantity points, often indicated by positive/negative signs or angles.
Example:
When a compass needle points north, it indicates the direction of the Earth's magnetic field.
Displacement
The change in an object's position, representing the straight-line distance and direction from the starting point to the ending point.
Example:
If you start at home, walk 5 km east to a friend's house, and then return home, your total displacement is 0 km.
Distance
The total path length traveled by an object, regardless of its starting or ending position.
Example:
If you walk 5 meters forward and then 3 meters backward, your total distance traveled is 8 meters.
Magnitude
The size or numerical value of a physical quantity, regardless of its direction.
Example:
If a car is traveling at 60 mph, 60 mph is the magnitude of its speed.
Position
The location of an object relative to a chosen origin or reference point.
Example:
If your classroom is 15 meters east of the main entrance, that describes its position relative to the entrance.
Resultant vector
Another term for the vector sum, representing the net effect of multiple vectors acting together.
Example:
After walking 3 km north and then 4 km east, your resultant vector of displacement from your starting point would be 5 km northeast.
Scalars
Quantities that are fully described by their magnitude (size) alone, without any associated direction.
Example:
When you check the thermometer, the temperature reading of 25°C is a scalar quantity because it only tells you 'how much' heat, not a direction.
Speed
The rate at which an object covers distance, calculated as distance divided by time.
Example:
A cheetah running 100 meters in 4 seconds has an average speed of 25 m/s.
Vector sum
The single resultant vector that represents the combined effect of two or more individual vectors.
Example:
If you push a box with 10 N of force to the right and a friend pushes with 5 N to the left, the vector sum of the forces is 5 N to the right.
Vectors
Quantities that are described by both magnitude (size) and direction.
Example:
To navigate a treasure hunt, you need vectors like 'walk 10 paces north' because both the distance and direction are crucial.
Velocity
The rate of change of an object's position, including both its speed and its direction of motion.
Example:
A car moving at 60 mph east has a different velocity than a car moving at 60 mph west, even though their speeds are the same.