RBSE Class 11 Physics Notes Chapter 3 Motion in a Straight Line

These comprehensive RBSE Class 11 Physics Notes Chapter 3 Motion in a Straight Line will give a brief overview of all the concepts.

Rajasthan Board RBSE Solutions for Class 11 Physics in Hindi Medium & English Medium are part of RBSE Solutions for Class 11. Students can also read RBSE Class 11 Physics Important Questions for exam preparation. Students can also go through RBSE Class 11 Physics Notes to understand and remember the concepts easily.

RBSE Class 11 Physics Chapter 3 Notes Motion in a Straight Line

Frame of Reference:
Any stationary point or place with respect to which, the position, velocity, acceleration etc. of an object are measured, is called ‘Frame of Reference’.

These are of following three types:

• Cartesian frame of reference
• Spherical frame of reference
• Cylindrical frame of reference.

State of Rest:
If the position of an object does not change with respect to a frame of reference, then the object is said to be in state of rest.

State of Motion:
If the position of an object changes with time with respect to a frame of reference, then it is said to be in state of motion.

Types of Motion:
There are three types of motion:

• Translational motion,
• Rotational motion,
• Vibrational motion.

Motion in a Straight Line:
If an object moves in straight line, then this motion is called motion in a straight line.

Distance and Displacement:

• Distance: The length of path actually adopted by moving body is called distance. It is scalar quantity.
• Displacement: The minimum distance between initial and final positions of the body is called its displacement. It is vector quantity.

Speed:
The distance travelled per unit time, is called speed, i. e. rate of change of distance with time is called speed. It is scalar quantity.

Velocity:
Rate of change of displacement is called velocity. It is vector quantity.

Acceleration:
Rate of change of velocity is called acceleration i.e.,
Acceleration = $$\frac{\text { Change in velocity }}{\text { Time }}$$

• Slope of distance-time graph provides speed and that of displacement-time graph provides velocity.
• The area covered by graphical line and time axis in acceleration-time graph provides the velocity of the object, i.e. $$\vec{v}=\int_{t_1}^{t_2}$$a.dt

Stopping Distance of Vehicles:
The distance travelled by a vehicle after applying the breaks and before becoming at rest, is called stopping distance.

Reaction Time:
The time between observing an event and reacting accordingly is called reaction time.

Relative Velocity:
The measurement of velocity of an object with respect to other moving object is called relative velocity, i.e. relative velocity of B with respect to A.
VBA = VB - VA

→ Instantaneous speed v = $$\frac{d S}{d t}$$

→ Instantaneous velocity $$\vec{v}=\frac{v \vec{S}}{d t}$$

→ Average speed
vav = $$\frac{\text { Totaldistance }}{\text { Total time }}=\frac{S_1+S_2+S_3+\ldots .}{t_1+t_2+t_3+\ldots \ldots}$$

→ Velocity of the particle by acceleration-time graph,
vav = $$\frac{S}{\frac{S_1}{v_1}+\frac{S_2}{v_2}+\frac{S_3}{v_3}+\ldots}$$

→ When time is constant then
vav = $$\frac{v_1+v_2+v_3+\ldots \ldots+v_n}{n}$$

→ Acceleration, a = $$\frac{\text { Change in velocity }}{\text { Time }}=\frac{v-u}{t}$$

→ Instantaneous acceleration, a = $$\frac{d v}{d t}=\frac{d^2 S}{d t^2}$$

→ Slope of displacement-time graph provides velocity
v = tan θ = $$\frac{d x}{d t}$$

→ Displacement of the particle in velocity - time graph,
$$\overrightarrow{\Delta S}=\int_{t_1}^{t_2} v \cdot d t$$

→ Velocity of the particle by acceleration-time graph,
$$\vec{v}=\int_{t_1}^{t_2} a \cdot d t$$

→ Equation of uniformly accelerated motion,

• v = u + at
• S = ut + $$\frac{1}{2}$$ at2
• v2 = u2 + 2aS

→ Distance travelled in tth second.
Stth = u + $$\frac{1}{2}$$a(2t - 1)

→ Reaction time, t = $$\sqrt{\frac{2 d}{g}}$$

→ Relative velocity,

• Relative velocity of A with respect to B
VAB = VA - VB
• Relative velocity of B with respect to A,
VBA = VB - VA

→ Stopping distnace of vehicles
S.D = $$\frac{u^2}{2 a}$$

→ Frame of reference: Any stationary point or place with respect to which the position, velocity, acceleration etc. of an object are measured, is called frame of reference.

→ Distance: Length of path actually adopted by a moving body is called distance.

→ Displacement: Minimum distance between initial and final positions is called displacement.

→ Speed: Rate of change of distance with time is called speed.

→ Velocity: Rate of change of displacement with time is called velocity.

→ Acceleration: Rate of change of velocity with time is called acceleration.

→ Stopping distance: The distance travelled by the moving vehicle after applying breaks upto becoming at rest, is called stopping distance.

→ Relative velocity: The velocity of a moving object measured by moving observer is called relative velocity.

Last Updated on Oct. 14, 2022, 5:42 p.m.
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Published Oct. 14, 2022