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Frame Of Reference Motion In A Straight Line Uniform L-1
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Frame of Reference, Motion in a Straight Line, Uniform Motion
![image](https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/physics-class-11-unit-03-chapter-02-frame-of-reference-motion-in-a-straight-line-lecture-2_4-zjhtgc8aqtk-015-0040.8.jpg)
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Graphical description of displacement v/s time
- Straight line equal distance in equal interval of time.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Motion
- **Motion could be more complex** - Car which starts from rest, starts to move, then it moves ot uniform motion,
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Motion
- How fast is position changing with time? - speed, include directional aspect $\rightarrow$ velocity
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Average velocity
- $\text { Average velocity }=\frac{\text { change in displacement }}{\text { change in time }}$ - If the displacement over time interval - $ \Delta t=\Delta x $ - $ \text { Then average velocity }$ - $\quad$$\quad$$=\frac{\Delta x}{\Delta t} $ - $\quad$$ \bar{V}=\frac{x_2-x_1}{t_2-t_1}$.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Unit of Average velocity
- Units of average velocity $=\frac{\text { Length }}{\text { Time }} = \frac{L}{T}$ - ${SI} = \frac{m}{s}$ - Another unit $\frac{\mathrm{km}}{\mathrm{hr}}$
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Average velocity
- Average velocity $\rightarrow$ vector quantity motion along a straight line $\rightarrow$ direction is given by sign of displacement. - $ \bar{v}=\frac{x_2-x_1}{t_2-t_1} $ - $ \Delta t=t_2-t_1 $ - $ P Q \rightarrow \text { Straight line } $ - $ \text { Slope of line } $
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Slope of Line
- $ \bar{v}$ can be positive, negative and zero.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Instantaneous Velocity and Speed
- $\text { It }_{\Delta t \rightarrow 0} \frac{\Delta x}{\Delta t}=v \quad\$Instantaneous velocity - rate of change of position with respect fo time.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Instantaneous Velocity and Speed
- $\frac{\Delta x}{\Delta t} \rightarrow$ approach tangent to the $x-t$ curve at $t_1$ - $\text { If } \Delta t \rightarrow 0 .$ - tangent/slope of $x-t$ curve at $t=t$, gives velocity or instantaneous velocity at $t=t_1$
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Motion
- **Motion could be more complex** - Car which starts from rest, starts to move, then it moves at uniform motion,
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Instantaneous Velocity and Speed
- Magnitude of Instantaneous Velocity = Instantaneous Speed. - Velocity may not be constant. - Rate of change of velocity with time as accelaration.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Motion
- **Motion could be more complex** - Car which starts from rest, starts to move, then it moves at uniform motion,
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Negative Accelerant
- Curve Upwards - $\leftarrow$ negative accelerant - straight line x - t - ${\Rightarrow} a=0$
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Displacement
- $ x \rightarrow t $ - $ \frac{d \vec{x}}{d t}=\vec{v} $ - $ \frac{d x}{d t}=v $ - $ \frac{d v}{d t}=a$
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Displacement
- $ x \rightarrow t$ - $ \frac{d x}{d t}=v $ - $ x-t$ curve slope = v - $ \int{ d x}=\int v d t $ - $x_2-x_1$ - Area under $v-t$ curve: displacement.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Change of Velocity
- $\frac{d v}{d t}=a $ - $\int d v=\int a d t$ - Slope of $v-t$ curve gives a Area under $a-t$ curve gives velocity $\rightarrow$ change of velocity.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Chain Rule
- If acceleration known as a funchon of $x$. - $\frac{d v}{d t}=a$ - Chain Rule of Differentiation - $\frac{d v}{d t} =\frac{d v}{d x} \cdot \frac{d x}{d t}= \frac{v d v}{d x} $ - $ =\frac{1}{2} \frac{d}{d x}\left(v^2\right)$.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Chain Rule
- $\frac{1}{2} \frac{d}{d x}\left(v^2\right) =a $ - $ \int \frac{1}{2} d\left(v^2\right) =\int a d x$ - $ \left.\frac{1}{2} v^2\right|_1 ^2 =\int a d x $ - $ =\frac{1}{2}\left(v_2^2-v_1^2\right)$ - $ =\int a d x$.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- $a$ is constant relation between displacement $x$, time taken $t$, initial velocity $v_0$, final velocity $v$ and acceleration $a$. - acceleration = ${a}\leftarrow $ constant
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- $a=\frac{v-v_0}{t} $ - $ v=v_0+a t $ - Area of triangle = $\frac{1}{2}(v-v_0) t $ - displacement - Area under $ {v-t}$ curve - Area $=v_0 t+\frac{1}{2}\left(v- v_0\right) t $ - displacement = $v_0 t+\frac{1}{2} a t^2$
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- $a$ is constant relation between displecemend $x$, time taken $t$, initial velocity $v_0$, firal velocity $v$ and acceleration $a$. - acceleration = ${a}\leftarrow $ constant
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- $a=\frac{v-v_0}{t} $ - $ v=v_0+a t $ - $\frac{1}{2}(v-v_0) t $ - displacement - Area under $ {v-t}$ curve. - Area $=v_0 t+\frac{1}{2}\left(v- v_0\right) t $.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- $ x =v_0 t+\frac{1}{2} a t^2 $ - $ x =\left(\frac{v+v_0}{2}\right) t$ - $ x =\frac{\left(v+v_0\right)}{2} \frac{\left(v-v_0\right)}{a} $ - $ x =\frac{v^2-v_0^2}{2 a} $ - $ v^2 =v_0^2+2 a x$.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- $a=\frac{v-v_0}{t} $ - $ v=v_0+a t $ - $\frac{1}{2}(v-v_0) t $ - displacement - Area under $ {v-t}$ curve - Area $=v_0 t+\frac{1}{2}\left(v- v_0\right) t $ - displacement - $=v_0 t+\frac{1}{2} a t^2$.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- $ x =v_0 t+\frac{1}{2} a t^2 $ - $ x =\left(\frac{v+v_0}{2}\right) t$ - $ x =\frac{\left(v+v_0\right)}{2} \frac{\left(v-v_0\right)}{a} $ - $ x =\frac{v^2-v_0^2}{2 a} $ - $ v^2 =v_0^2+2 a x$.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- $ v=v_0 + a t $ $\longrightarrow(x - x_0)$ missing - $x=v_0 t+\frac{1}{2} a t^2 $ $\longrightarrow v $ missing - $ v^2=v_b^2+2 a x $ $\longrightarrow t $ missing - Valid only if $a=$ constant - $x \rightarrow$ displacement - $x_0 \neq 0$ - In above formulae $x_0=0$. - If $x_0 \neq 0 \rightarrow x$ replaced by $(x-x_0)$.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Uniform Acceleration
- Sign of $a$ - If velocity increasing in direction of positive $x,$ - $ a$ is positive. - If velocity decreasing in direction of positive $x$, - $a$ is negative (retardation).
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Free Fall
- Body falling under influence of gravity near earth's surface acceleration is constant $=g$ from the body toward the surface of earth.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Free Fall
- $g = 9.8 \frac{m}{s^2}$ - or - $g = 10 \frac{m}{s^2}$ - -ve sign downward directon. - +ve sign upward diredton.
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Frame Of Reference Motion In A Straight Line Uniform L-1
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Free Fall
- $\downarrow y \quad $ If you choose y as downwards - $a=+g$
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Frame Of Reference Motion In A Straight Line Uniform L-1
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