List of top Physics Questions

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 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 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 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 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 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 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 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
A radioactive element $_{90}X^{238}$ decay into $_{83}Y^{222}$ . The no of $\beta$ particles emitted are
A pure resistive circuit element $X$ when connected to an ac supply of peak voltage $200\,V$ gives a peak current of $5\,A$ which is in phase with the voltage. A second circuit element $Y$, when connected to the same ac supply also gives the same value of peak current but the current lags behind by $90^?$. If the series combination of $X$ and $Y$ is connected to the same supply, what will be the rms value of current?
A proton of energy 2 MeV is moving perpendicular to uniform magnetic field of 2.5 T. The force on the proton is $(Mp = 1.6 \times 10^{27}\, Kg$ and $q_p = e = 1.6 \times 10^{-19}C)$
A proton pf energy 8eV is moving in a circular path in a uniform magnetic field. The energy of an alpha particle moving in the same magnetic field and along the sathe path will be
A police van moving on a highway with a speed of $ 30\, km\, h^{-1} $ fires a bullet at a thief?s car speeding away in the same direction with a speed of $ 192\, km\, h^{-1} $ . If the muzzle speed of the bullet is $ 150 \,m \,s^{-1} $ , with what speed does the bullet hit the thief?s car ?
A point $P(\sqrt3R,0,0)$ lies on the axis of a ring of a mass 'M' and radius 'R'. The ring is located in y-z plane with its centre at origin 'O'. A small particle of mass 'm' starts from 'P' and reaches 'O' under gravitational attraction only. Its speed at 'O' will be
A point mass $m$ is placed inside a spherical shell of radius $R$ and mass $M$ at a distance $\frac{R}{2}$ from the centre of the shell. The gravitational force exerted by the shell on the point mass is
A player throws a ball vertically upwards with velocity $u$. At highest point,
A plate of mass $m$, length $b$ and breadth $a$ is initially lying on a horizontal floor with length parallel to the floor and breadth perpendicular to the floor. The work done to exect it on its breadth is
A plane progressive wave is given by y= 2 cos 6.284(330 t - x). What is period of the wave?