Home
Class 12
PHYSICS
Image of an object approaching a convex ...

Image of an object approaching a convex mirror of radius of curvature 20m along its optical axis is observed to move from `(25)/(3)`m to `(50)/(7)`m in 30 seconds. What is the speed of the object in km per hour?

Text Solution

Verified by Experts

The correct Answer is:
3
`(1)/(v) + (1)/(u) = (1)/(f) implies f = (R)/(2) = -10m`
`1^(st)` condition `(-3)/(25) + (1)/(u_(1)) = (-1)/(10) implies u_(1) = 50 m`
`2^(nd)` condition `(-7)/(50) + (1)/(u_(2)) = -(1)/(10) implies u_(2) = 25 `m
Velocity = `(triangleu)/(triangle t) = (25)/(30) xx (18)/(5) = 3km//h`
Promotional Banner

Topper's Solved these Questions

Similar Questions

Explore conceptually related problems

A balloon is rising up along the axis of a concave mirror of radius of curvature 20 m A ball is dropped from the balloon at a height 15m from the mirror when the balloon has velocity 20m//s .Find the speed of the image of the ball formed by concave mirror after 4 seconds[take: g=10m//s^(2) ]

A small object is placed 50 cm to the left of a thin convex lens of focal length 30 cm. A convex spherical mirror of radius of curvature 100 cm is placed to the right of the lens at a distance of 50 cm. The mirror is tilted such that the axis of the mirror is at an angle theta =30degree to the axis of the lens, as shown in the figure If the origin of the coordinate system is taken to be at the centre of the lens, the coordinates (in cm) of the point (x,y) at which the image is formed are

In the figure shown L is converging lens of focal length 10 cm and M is a concave mirror of radius of curvature 20 cm . A point object O is placed in front of the lens at a distance 15 cm . AB and CD are optical axes of the lens mirror respectively. Find the coordinates of the final image formed by this system taking O as origin. The distance between CD & AB is 1mm.

A cyclist is riding with a speed of 27 km /h . As he approaches a circular turn on the road of radius 80 m , he applies brakes and reduces his speed at the constant rate of 0.50m//s every second . What is the magnitude and direction of the net acceleration of the cyclist on the circular turn ?

A convex mirror and convex lens of radius of curvature 20 cm are placed on same axis with 30 cm separation. A point-like object is placed at 20 cm from convex lens and its image by this combination is obtained at object. What will be focal length of convex lens ?

An object approaches a convergent lens from the left of the lens with a uniform speed 5 m/s and stops at the focus. The image

In the figure shown S is a point monochromatic light source of frequency 6xx10^(14)Hz .M is a concave mirror of radius of curvature 20 cm and L is a thin converging lens of focal length 3.75 cm AB is the principal axis of M and L. Light reflected from the mirror and refracted from the lens in succession reaches the screen. An interference pattern is obtained on the screen by this arrangement. Q. Distance between two coherent sources whichmakes interference pattern on the screen is

In the figure shown S is a point monochromatic light source of frequency 6xx10^(14)Hz .M is a concave mirror of radius of curvature 20 cm and L is a thin converging lens of focal length 3.75 cm AB is the principal axis of M and L. Light reflected from the mirror and refracted from the lens in succession reaches the screen. An interference pattern is obtained on the screen by this arrangement. Q. Fringe width is

In the figure shown S is a point monochromatic light source of frequency 6xx10^(14)Hz .M is a concave mirror of radius of curvature 20 cm and L is a thin converging lens of focal length 3.75 cm AB is the principal axis of M and L. Light reflected from the mirror and refracted from the lens in succession reaches the screen. An interference pattern is obtained on the screen by this arrangement. Q. If the lens is replaced by another converging lens of focal length (10)/(3)cm and the lens is shifted towards right by 2.5 cm then