Physics Lecture: Motion and Kinematics

Vocabulary terms and definitions covering the fundamentals of motion, including displacement, speed, velocity, acceleration, and graphical analysis.

Rest

The state of an object if it does not change its position with time.

Motion

The state of an object if it changes its position with respect to time.

Reference point

The origin or starting point from where the object started its motion.

Distance

The total path length covered by an object; it is a scalar quantity and is always positive or zero.

Displacement

The shortest distance between the initial and final position; it is a vector quantity that can be positive, negative, or zero.

Scalar quantity

A quantity that has only magnitude.

Vector quantity

A quantity that has both magnitude and direction.

Metre ($m$)

The SI unit for both distance and displacement.

Uniform motion

Motion where the object covers equal distance in equal intervals of time.

Non-uniform motion

Motion where the object covers unequal distance in equal intervals of time.

Speed ($v$)

The distance travelled by the object per unit time; calculated as $\text{Speed} = \frac{\text{Distance}}{\text{Time}}$.

Average speed

The total distance travelled by the object divided by the total time taken.

Average Velocity ($v_{avg}$)

The change in position or displacement ($s$) divided by the time interval ($t$) in which the displacement occurs, expressed as $v_{avg} = \frac{s}{t}$.

Acceleration ($a$)

The change in velocity per unit time, calculated using the formula $a = \frac{v - u}{t}$ where $u$ is initial velocity and $v$ is final velocity.

$$m/s^2$$

The SI unit of acceleration.

Uniform acceleration

When the velocity of an object increases or decreases by equal amounts in equal intervals of time.

Non-uniform acceleration

When the velocity of an object increases or decreases by unequal amounts in equal intervals of time.

Retardation

Negative acceleration that occurs when the velocity of the object decreases with time.

Slope of a position-time graph

A value used to calculate the average velocity or speed of an object.

Slope of a velocity-time graph

A value used to calculate the acceleration of the object.

Area under a velocity-time graph

A value used to calculate the displacement of the object.