Glossary
2D Collisions
Collisions where objects move and interact in a two-dimensional plane, requiring the analysis of momentum components in both x and y directions.
Example:
When two pucks collide on an air hockey table and scatter at angles, it's a 2D collision requiring vector analysis.
Collisions
Interactions between two or more objects that involve an exchange of energy and momentum over a short period.
Example:
When a bowling ball strikes pins, it's a collision where momentum and energy are transferred.
Conservation of Momentum
A fundamental principle stating that if the net external force on a system is zero, the total momentum of the system remains constant before and after an interaction.
Example:
In a rocket launch, the total conservation of momentum means the momentum of the expelled exhaust gases equals the momentum gained by the rocket in the opposite direction.
Elastic Collisions
A type of collision where both the total momentum and the total kinetic energy of the system are conserved.
Example:
A perfectly bouncy superball hitting a hard floor and rebounding with nearly the same speed demonstrates an elastic collision.
Inelastic Collisions
A type of collision where the total momentum of the system is conserved, but the total kinetic energy is not, often due to energy conversion into heat, sound, or deformation.
Example:
When a dart sticks into a target, it's an inelastic collision because kinetic energy is lost as the dart deforms and embeds itself.
Kinetic Energy (KE)
The energy an object possesses due to its motion, calculated as half the product of its mass and the square of its velocity.
Example:
A roller coaster at the bottom of a hill has maximum kinetic energy as it moves at its fastest speed.
Momentum
A vector quantity defined as the product of an object's mass and its velocity, representing the 'quantity of motion' an object possesses.
Example:
A heavy truck moving slowly can have more momentum than a light car moving fast, making it harder to stop.
Scalar
A physical quantity that has only magnitude and no direction, such as mass, time, and kinetic energy.
Example:
The temperature outside is 25 degrees Celsius; it's a scalar quantity because it doesn't have a direction.
Vector
A physical quantity that has both magnitude and direction, such as momentum, velocity, and force.
Example:
To describe the velocity of a car, you need to state both its speed (magnitude) and its direction (e.g., 60 mph north), making velocity a vector.