Acceleration and Kinematics Vocabulary

Key vocabulary terms and definitions from the lecture on acceleration and kinematics.

Acceleration

Rate of change of velocity; a vector quantity; a = Δv/Δt (units m/s^2).

Velocity

Rate of change of position; has magnitude and direction; a vector; sign indicates the chosen direction.

Initial velocity (vi)

Velocity at the start of the interval.

Final velocity (vf)

Velocity at the end of the interval.

Initial time (ti)

Time at the start of the interval.

Final time (tf)

Time at the end of the interval.

Δt

Change in time; tf − ti.

Δv

Change in velocity; Δv = vf − vi.

Acceleration formula

a = (vf − vi) / (tf − ti) – acceleration as the rate of change of velocity over time.

Positive direction

The arbitrarily chosen forward direction; signs of velocity and acceleration follow this convention.

Same direction (v and a)

If velocity and acceleration have the same sign, speed increases.

Opposite direction (v and a)

If velocity and acceleration have opposite signs, speed decreases.

Upward throw sign convention

In vertical motion, upward is positive; velocity is positive while moving up; acceleration due to gravity is negative.

Displacement sign

Displacement sign depends on location relative to the origin; positive if in the positive direction.

Highest point in vertical throw

At the top, velocity is zero; acceleration remains downward (negative).