Class 11 Physics: Motion in a Straight Line Flashcards

Comprehensive vocabulary flashcards covering basic mechanics, displacement, velocity, calculus-based kinematics, gravitational motion, graph rules, and relative motion based on Prashant Kirad's lecture.

Mechanics

A branch of physics that deals with the study of motion of objects, divided into kinematics and dynamics.

Kinematics

The branch of mechanics that focuses on the motion of objects without considering the forces causing the motion.

Dynamics

The branch of mechanics that deals with the study of motion along with the forces and causes responsible for it.

Frame of Reference

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

Scalar Quantity

A physical quantity that possesses magnitude only and lacks direction.

Vector Quantity

A physical quantity that possesses both magnitude and direction.

Distance

The actual path length traveled by a moving object; it is a scalar quantity and is always positive.

Displacement

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

Circular Arc Displacement Formula

The formula used to calculate displacement across a circular arc of radius $r$ subtending an angle $\theta$, given by $\text{Displacement} = 2 r \tan\theta$ or $2 r \tan\theta$.

Speed

The rate of change of distance traveled by an object per unit time, given by $\text{Speed} = \frac{\text{Total Distance}}{\text{Total Time}}$.

Uniform Speed

The speed of an object when it covers equal distances in equal intervals of time.

Non-Uniform Speed

The speed of an object when it covers unequal distances in equal intervals of time, indicating a changing rate of motion.

Velocity

A vector quantity defined as the rate of change of displacement with respect to time ($\text{Velocity} = \frac{\text{Displacement}}{\text{Time}}$), with SI unit $\text{m/s}$ and dimensional formula $LT^{-1}$.

Average Speed

The ratio of the total distance traveled by an object to the total time taken for the journey.

Average Velocity

The ratio of the total displacement of an object to the total time taken.

Round-Trip Average Speed Formula

The formula for the average speed of an object traveling from point A to B at speed $v_1$ and returning at speed $v_2$, given by $v_{\text{avg}} = \frac{2 v_1 v_2}{v_1 + v_2}$.

Acceleration

The rate of change of velocity per unit time ($a = \frac{v - u}{t}$), with SI unit $\text{m/s}^2$ and dimensional formula $LT^{-2}$.

Retardation

Negative acceleration that occurs when the speed or velocity of a moving object decreases over time.

Instantaneous Velocity

The velocity of an object at a specific moment or instant in time, expressed mathematically as $v = \frac{dx}{dt}$.

Instantaneous Acceleration

The acceleration of an object at a specific instant in time, expressed mathematically as $a = \frac{dv}{dt} = \frac{d^2x}{dt^2}$ or $a = v \frac{dv}{dx}$.

First Equation of Motion

The kinematic equation relating final velocity, initial velocity, uniform acceleration, and time: $v = u + a t$.

Second Equation of Motion

The kinematic equation relating displacement, initial velocity, uniform acceleration, and time: $s = u t + \frac{1}{2} a t^2$.

Third Equation of Motion

The kinematic equation relating final velocity, initial velocity, uniform acceleration, and displacement: $v^2 - u^2 = 2 a s$.

Displacement in the $n^{\text{th}}$ Second

The distance covered specifically during the $n^{\text{th}}$ second interval of motion, calculated as $S_n - S_{n-1}$.

Hitting Velocity of a Dropped Object

The velocity with which an object dropped from rest from a height $h$ strikes the ground under free fall, given by $v = \frac{u^2}{2 g}$ or $v = \tan\theta$.

Time of Fall for a Dropped Object

The time taken for an object released from rest at height $h$ to reach the ground under gravity, given by $t = \tan\theta$.

Maximum Height of a Vertically Thrown Object

The peak height $h$ reached by an object projected vertically upward with an initial velocity $u$, given by $h = \frac{u^2}{2 g}$.

Total Time of Flight (Vertical Motion)

The total time spent in the air by an object thrown vertically upward with velocity $u$ to return to the initial level, given by $T = \frac{2 u}{g}$.

Galileo's Ratio (Law of Odd Numbers)

The principle stating that the distances covered by an object falling from rest under uniform gravity in equal successive time intervals are in the ratio of consecutive odd numbers ($1 : 3 : 5 : 7 \tan\theta$).

Slope of Displacement-Time Graph

The steepness or tangent of the angle ($\text{Slope} = \tan(x)$ or $\tan(\theta)$) on a displacement-time graph, which represents the velocity of the object.

Area Under Velocity-Time Graph

The total area enclosed between the curve on a velocity-time graph and the time axis, which represents the displacement of the object.

Area Under Acceleration-Time Graph

The enclosed region between the acceleration curve and the time axis, which represents the total change in velocity.

Relative Velocity (Same Direction)

The velocity of object A relative to object B when both objects move in the same direction, calculated as $v_{AB} = v_A - v_B$.

Relative Velocity (Opposite Direction)

The velocity of object A relative to object B when moving towards each other or in opposite directions, calculated as $v_{AB} = v_A + v_B$.