Physics chapter 2

Reference Frame

The coordinate system or perspective from which position, distance, or speed is measured; all motion measurements are relative to one.

Displacement

The change in position of an object, regardless of the path taken; calculated as Δx = x₂ − x₁. It can be positive or negative depending on direction.

Distance Traveled

The total length of the actual path covered by an object, measured along that path rather than straight-line change in position.

Speed (Average)

How far an object travels in a given time interval; average speed = distance traveled / time elapsed. Has no direction.

Velocity (Average)

Displacement divided by time elapsed; includes directional information (positive or negative), unlike speed.

Instantaneous Velocity

The average velocity in the limit as the time interval Δt approaches zero; velocity at a single moment in time.

Acceleration (Average)

The rate of change of velocity; average acceleration = change in velocity / time elapsed.

Instantaneous Acceleration

The average acceleration in the limit as the time interval Δt approaches zero.

Negative Acceleration

Acceleration directed in the negative direction as defined by the chosen coordinate system (not necessarily slowing down).

Deceleration

Occurs when acceleration is opposite in direction to velocity, causing an object's speed to decrease.

Constant Acceleration Equation (v = v₀ + at)

Relates final velocity to initial velocity, acceleration, and time, for motion with constant acceleration.

Constant Acceleration Equation (x = x₀ + v₀t + ½at²)

Gives final position in terms of initial position, initial velocity, time, and constant acceleration.

Constant Acceleration Equation (v² = v₀² + 2a(x − x₀))

Relates velocity and position without needing time directly, for constant acceleration.

Average Velocity Formula (v̄ = (v + v₀)/2)

For constant acceleration, average velocity equals the mean of initial and final velocity.

Freely Falling Object

An object moving under the influence of gravity alone (no air resistance), experiencing constant downward acceleration.

Acceleration Due to Gravity (g)

The acceleration experienced by objects near Earth's surface due to gravity, approximately 9.80 m/s², directed downward.

Kinematics

The branch of physics describing how objects move, without regard to the forces causing the motion.

Slope of an x-t Graph

Represents velocity; on a position-vs-time graph, the steepness of the line at any point gives the object's velocity at that point.