Motion Lecture Notes

A set of vocabulary flashcards based on Grade 9 Physics lecture notes covering kinematics, dynamics, types of motion, and circular motion.

Mechanics

The branch of physics that studies motion, broken down into two parts: kinematics and dynamics.

Kinematics

The study of how objects move without concerning the causes of their motion.

Dynamics

The study of the causes of motion, specifically the study of forces.

Reference Point

A starting point, also called the origin, used to describe the position of an object.

Motion

The act or process of an object changing its position compared to a fixed object over time.

Rest

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

Translational Motion

Motion in which all points in a body follow parallel paths and the orientation of the object remains the same.

Rectilinear Motion

A type of translational motion where an object moves in a straight line, also known as one-dimensional motion.

Curvilinear Motion

A type of translational motion where an object moves along a curved path without a change in its orientation.

Rotational Motion

A motion in which an object spins about a fixed axis and its orientation continuously changes.

Rolling Motion

A combination of translational and rotational motion, such as the motion of a cycle wheel.

Uniform Motion

Motion where a body covers equal distances in equal intervals of time in a straight line in a particular direction, implying constant velocity.

Non-uniform Motion

Motion where the velocity of a body is variable, because the magnitude or direction of velocity changes.

Distance

A scalar quantity representing the length of the actual path between the initial and final positions of a moving object.

Displacement

A vector quantity defined as the shortest distance between the initial and final position of a particle, calculated as $\Delta x = x_f - x_i$.

Uniform Speed

A state where an object covers equal distances in equal intervals of time, keeping the magnitude of speed constant.

Average Speed

The ratio of the total distance travelled by an object to the total time taken.

Instantaneous Speed

The speed of a body at any specific instant of time, measured by a vehicle's speedometer.

Velocity

A vector quantity representing the rate of change of displacement.

Acceleration

A vector quantity representing the rate of change of velocity, occurring when magnitude, direction, or both change.

Retarded Motion

Motion where velocity and acceleration are in opposite directions, causing the velocity to decrease.

Free Fall

The motion of an object subject only to the influence of gravity, in the absence of air resistance.

Acceleration due to Gravity ($g$)

The constant acceleration of a freely falling body, approximately $9.8\,m/s^2$ on the surface of Earth.

Circular Motion

The motion of a particle moving along a circular path, which is always an accelerated motion due to continuous changes in velocity direction.

Angular Displacement ($\theta$)

The angle described by a particle moving along a circular path, measured in radians.

Angular Velocity ($\omega$)

The rate of change of angular displacement, measured in $rad/s$.

Centripetal Acceleration ($a_c$)

The radially inward acceleration required to move an object along a circular path, perpendicular to the velocity.

Centripetal Force

The radially inward force required to move an object along a circular path, calculated as $F = m \times a_c$.