Motion and Energy

Mechanical energy is defined as the sum of an object's kinetic energy and its potential energy. It represents the total energy associated with the motion and position of an object.

Acceleration occurs whenever velocity changes, including changes in speed or direction. A train that is not functioning (and presumably stationary) is not accelerating. The other options all describe situations where velocity is changing: changing speed, changing direction, or decelerating while stopping.

A vector is a quantity that has both magnitude and direction. Velocity is a vector because it specifies how fast an object is moving and in what direction, unlike speed or distance.

The standard formula for kinetic energy is 1/2 multiplied by mass multiplied by velocity squared (KE = 1/2mv^2).

Acceleration is defined as the rate of change of velocity over time, calculated as the change in velocity (final minus initial) divided by the time interval.

Velocity is a vector quantity involving both speed and direction. How far you travel (distance) is a scalar and does not inherently change the velocity vector.

Average speed is calculated by taking the total distance traveled and dividing it by the total time taken to cover that distance.

Motion is defined as a change in position relative to a fixed reference point. If an object's position does not change relative to that point, it is considered at rest.