Car B overtakes another car A at a relative speed of $40 \mathrm{~ms}^{-1}$. How fast will the image of car B appear to move in the mirror of focal length $10 \mathrm{~cm}$ fitted in car $\mathrm{A}$, when the car $\mathrm{B}$ is $1.9 \mathrm{~m}$ away from the car A?
$4 \mathrm{~ms}^{-1}$
$0.2 \mathrm{~ms}^{-1}$
$40 \mathrm{~ms}^{-1}$
$0.1 \mathrm{~ms}^{-1}$
Correct Option: , 4
Mirror used is convex mirror (rear-view mirror)
$\therefore \mathrm{V}_{\mathrm{L} / \mathrm{m}}=-\mathrm{m}^{2} \mathrm{~V}_{\mathrm{O} / \mathrm{m}}$
Given,
$\mathrm{V}_{\mathrm{O} / \mathrm{m}}=40 \mathrm{~m} / \mathrm{s}$
$m=\frac{f}{f-u}=\frac{10}{10+190}=\frac{10}{200}$
$\therefore \mathrm{V}_{1 / \mathrm{m}}=-\frac{1}{400} \times 40=-0.1 \mathrm{~m} / \mathrm{s}$
$\therefore$ Car will appear to move with speed $0.1 \mathrm{~m} / \mathrm{s}$.
Hence option (4)
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All Study Material
- JEE Main
- Exam Pattern
- Previous Year Papers
- PYQ Chapterwise
- Physics
- Kinematics 1D
- Kinemetics 2D
- Friction
- Work, Power, Energy
- Centre of Mass and Collision
- Rotational Dynamics
- Gravitation
- Calorimetry
- Elasticity
- Thermal Expansion
- Heat Transfer
- Kinetic Theory of Gases
- Thermodynamics
- Simple Harmonic Motion
- Wave on String
- Sound waves
- Fluid Mechanics
- Electrostatics
- Current Electricity
- Capacitor
- Magnetism and Matter
- Electromagnetic Induction
- Atomic Structure
- Dual Nature of Matter
- Nuclear Physics
- Radioactivity
- Semiconductors
- Communication System
- Error in Measurement & instruments
- Alternating Current
- Electromagnetic Waves
- Wave Optics
- X-Rays
- All Subjects
- Physics
- Motion in a Plane
- Law of Motion
- Work, Energy and Power
- Systems of Particles and Rotational Motion
- Gravitation
- Mechanical Properties of Solids
- Mechanical Properties of Fluids
- Thermal Properties of matter
- Thermodynamics
- Kinetic Theory
- Oscillations
- Waves
- Electric Charge and Fields
- Electrostatic Potential and Capacitance
- Current Electricity
- Thermoelectric Effects of Electric Current
- Heating Effects of Electric Current
- Moving Charges and Magnetism
- Magnetism and Matter
- Electromagnetic Induction
- Alternating Current
- Electromagnetic Wave
- Ray Optics and Optical Instruments
- Wave Optics
- Dual Nature of Radiation and Matter
- Atoms
- Nuclei
- Semiconductor Electronics: Materials, Devices and Simple Circuits.
- Chemical Effects of Electric Current,