Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NDA2026General AbilityGeneral ScienceActual

An object is placed far beyond the centre of curvature of a concave mirror. The object then starts accelerating towards the mirror. Which one of the following is correct?

Options

  1. AThe image will accelerate towards the centre of curvature.
  2. BThe image will accelerate towards the focus.
  3. CThe image will accelerate towards the pole of the mirror.
  4. DThe image will move with a constant speed towards the focus.

Correct answer

A. The image will accelerate towards the centre of curvature.

Step-by-step solution

Using the mirror formula: 1 v + 1 u = 1 f Differentiating with respect to time t , we get the velocity of the image v_i in terms of the velocity of the object v_o : - 1 v^2 dv dt - 1 u^2 du dt = 0 v_i = - ( v u )^2 v_o = - f^2 (u-f)^2 v_o Since the object is moving towards the mirror, u is increasing (becoming less negative), so v_o > 0 . This makes v_i To find the acceleration of the image a_i , we differentiate v_i with respect to t : a_i = dv_i dt = - f^2 (u-f)^2 a_o + 2f^2 (u-f)^3 v_o^2 Here, a_o > 0 because th

Practice General Science on Quantrex Academy →

More from General Science

For an object in gravitational field, the gravitational potential is the same at two points A and B , but the gravitational field is not the same at these two points. Which one of 2026A very large container consists of an ideal gas. The speed of sound in the gas is x . When the pressure of the gas is doubled while keeping the temperature constant, the speed of s 2026A constant power machine pulls a block on a smooth horizontal surface. Which one of the following correctly describes the relation between speed of the block (v) and time (t) ? 2026A ball is dropped from rest from height h above the ground in frame S (the Earth's frame). Another frame S' is moving upwards with constant speed u relative to the Earth. In frame 2026A pendulum of length L oscillates with an angular amplitude of = 60^ and time period T . Let T₀ = 2 L g be the time period for small angle of oscillations, where g is the accelerat 2026A solid of mass m has temperature-dependent specific heat as C(T) = C₀ + T , where C₀ and are constants. The solid is heated from T₁ to T₂ . Which one of the following is the corre 2026In a certain process, the relation between pressure (P) and volume (V) , for an ideal gas, is given by PV^2 = constant . If the initial temperature is T₁ and the final temperature 2026A person jumps from a height on soft sand. Which one of the following is the correct reason for less likely injury to the person? 2026 Full General Science list All NDA PYQs