Motion in a Straight Line Flashcards

Vocabulary-style flashcards covering kinematics, motion types, scalar/vector differences, and graphical analysis from Class 11th Physics notes.

Mechanics

The branch of physics that deals with the study of motion of objects, the forces responsible for the motion, and the conditions of bodies at rest.

Kinematics

A part of mechanics that focuses on how objects move without worrying about the forces causing the motion.

Dynamics

A part of mechanics that studies motion along with its causes, such as forces, to explain why objects move in a certain way.

Rest

The state of an object if its position does not change with respect to its surroundings or a reference point over time.

Motion

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

Frame of Reference

A system consisting of an origin and a coordinate axis relative to which the position and motion of an object are measured.

Point Object

An object whose size is much smaller than the distance it moves.

Scalar Quantity

A quantity that has only magnitude and obeys ordinary laws of algebra, such as distance, speed, mass, or time.

Vector Quantity

A quantity that has both magnitude and direction and does not obey ordinary algebra rules, requiring vector algebra, such as displacement, velocity, or force.

Distance ($d$)

The total path length travelled by an object during motion; it is a scalar quantity that is always positive or zero.

Displacement ($s$)

The shortest straight-line distance between the initial and final positions of an object; it is a vector quantity that can be positive, negative, or zero.

Speed

The rate of change of distance with respect to time, measured in the SI unit of $\text{m/s}$; it is a scalar quantity.

Uniform Speed

A state where an object covers equal distances in equal intervals of time, regardless of how small the intervals may be.

Non-Uniform Speed

A state where an object covers unequal distances in equal intervals of time, or equal distances in unequal intervals of time.

Velocity

The rate of change of displacement with respect to time; it is a vector quantity measured in $\text{m/s}$.Ordered pairs of magnitude and direction.

Uniform Velocity

A state where an object undergoes equal displacement in equal intervals of time while moving in a fixed direction.

Average Speed

$$\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time Taken}}$$

Average Velocity

$$\text{Average Velocity} = \frac{\text{Total Displacement}}{\text{Total Time Taken}}$$

Instantaneous Speed

The speed of an object at a particular instant of time; it is always a positive scalar quantity.

Instantaneous Velocity

The velocity of an object at a specific moment in time, defined as the limit of the average velocity as the time interval approaches zero.

Acceleration

The rate at which an object's velocity changes with respect to time, measured in $\text{m/s}^2$; it is a vector quantity.

Retardation

Also known as negative acceleration, which occurs when an object's velocity decreases as time progresses.

Distance in the $n^{th}$ Second ($S_n$)

The difference between the distance covered in $n$ seconds and $(n-1)$ seconds.

Slope of s-t Graph

The slope of a position-time graph represents the velocity of the object.

Slope of v-t Graph

The slope of a velocity-time graph represents the acceleration of the object.