List of top Physics Questions

A simple pendulum of length 1 m has a wooden bob of mass $ 1 \,kg $ . It is struck by a bullet of mass $ 10^{-2}\, kg $ moving with a speed of $ 2 \times 10^2\, ms^{-1} $ . The height to which the bob rises before swinging back is (Take $ g = 10 \,ms^{-2} $ )
A simple microscope consists of a concave lens of power 10D and a convex lens of power 15 D. Its magnification at near point is (least -distance-of distinct vision, D = 25 cm)
A set of atoms in an excited state decays
A second's [pendulum clock having steel wire is calibrated at 20$^{\circ}$C . When temperature is, increased to 30$^{\circ}$C, then how much time does the clock lose or gain in one week ? $[\alpha_{steel}=1.2 \times 10^{-5}(^{\circ}\,C)^{-1}]$:
A screen is placed $90\, cm$ away from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by $20 \,cm$. Find the focal length of lens.
A scooter of mass 120 kg is moving with a uniform velocity of $108\,km\,h^{-1}$. The force required to stop the vehicle in 10 s is
A screen is placed $50\, cm$ from a single slit which is illuminated with light of wavelength $6000 ?$. If the distance between the first and third minima in the diffraction pattern is $3.0 \,mm$. The width of the slit is
A satellite launching station should be
A saturn year is $29.5$ times the earth year. How far is the saturn from the sun if the earth is $1.5 \times 10^8\, km$ away from the sun?
A running man has half the kinetic energy than a boy of half his mass has. The man speed up by $1.0\, ms^{-1}$ and then he has the same energy as the boy. The original speeds of the man and boy respectively are
A rope thrown over a pulley has a ladder with a man of mass m on one of its ends and a counter balancing mass M on its other end. The man climbs with a velocity $V_r$ relative to ladder . Ignoring the masses of the pulley and the rope as well as the friction on the pulley axis, the velocity of the center of mass of this system is :
A rod of length 20 cm is made of metal . It expands by 0.075 cm when its temperature is raised from $0^{\circ} C$ to $100^{\circ} C$ . Another rod of a different metal B having the same length expands by 0.045 cm for the same change in temperature . A third rod of the same change in temperature . A third rod of the same length is composed of two parts , one of metal A and the other of metal B. This rod expands by 0.060 cm for the same change in temperature . The portion made of metal A has the length :
A rocket of mass 1000 kg is to be projected vertically upwards. The gases are exhausted vertically downwards with velocity 100 $ms^{-1} $ with respect to the rocket. What is the minimum rate of burning of fuel, so as to just lift the rocket upwards against the gravitational attraction? (Take g = 10 $ms^{-2} )$
A rocket of initial mass $6000 \,kg $ ejects gases at a constant rate of $16\, kg$ $s^{-1}$ with constant relative speed of $11 \,km$ $s^{-1}$. What is the acceleration of the rocket one minute after the blast ?
A river is flowing from west to east with a speed $5\,m\,s^{-1}$. A swimmer can swim in still water at a speed of $10\,ms^{-1}$. If he wants to start from point $A$ on south bank and reach opposite point $B$ on north bank, in what direction should he swim?
A rigid body is said to be in partial equilibrium, when it is in
A rider on horseback falls forward when the horse suddenly stops. This is due to
A reflecting telescope has a large mirror for its objective with radius of curvature equal to $80 \,cm$. The magnifying power of this telescope if eye piece used has a focal length of $1.6 \,cm$ is
A real image is formed by a convex lens. If we put it in contact with a concave lens and the combination again forms a real image which of the following is true for the new image from the combination ?
A ray of light incident normally.on first face of prism and the emergent ray grazes the second surface. If A is angle of the prism and C is its critical angle then the correct choice is
A ray of light takes grazing incidence on the first face of a prism and the emergent ray is normal to the 2nd face of the prism. If D is angle of deviation then the refracting angle of the prism is equal to
A raindrop of mass $1\, g$ falling from a height of $1 \,km$ hits the ground with a speed of $50\, ms$ . If the resistive force is proportional to the speed of the drop, then the work done by the resistive force is (Take $g= 10 \,ms^{-2}$)
A rain drop of radius $ 0.3 \,mm $ falls through air with a terminal velocity of $ 1 \,m \,s^{-1} $ . The viscosity of air is $ 18 \times 10^{-5 } $ poise. The viscous force on the rain drop is
A radioactive substance with decay constant of $0.5\, s^{-1}$ is being produced at a constant rate of 50 nuclei per second. If there are no nuclei present initially, the time (in second) after which 25 nuclei will be present is
A radioactive nucleus can decay by two different processes. The half life for the first process is 2t and that for the second process is t. The effective disintegration constant of nucleus is