Recent questions and answers in physics

A wax candle floats vertically in a liquid of density twice that of wax. The candle burns at the rate of 4 cm/hr. Then, with respect to the surface of the liquid the upper end of the candle will:

Two generators `S_1` and `S_2` produce water wave of equal frequency. A point P is located such that `(S_1P-S_2P)` is equal to half a wavelength. When operated alone, `S_1` produces an oscillation of amplitude 2a at P while `S_2` produces an oscillation of amplitude a. If the generators are operated in phase, which graph correctly shows the resultant oscillation at P?

A shooting game involves using a gun that fires by itself at random times. The player can only point the gun in a fixed direction while the target moves, as shown. At which of the given region should the player aim in order to score the greatest number of hits?

A uniform solid sphere of mass m is being pulled on a horizontal surface with force F parallel to the surface and applied at its top most point. If the acceleration of the cylinder is a & it is rolling on the surface, the value of F is:

A cylindrical block of wood of base area 30 `cm^2`, floats in a liquid of density 900 kg/`m^3`. The block is depressed lightly and then released. The time period of the resulting oscillations of the block is equal to that of spring with block of same mass, then spring constant is equal to:

In case of an adiabatic process the correct relation in terms of pressure p and density `rho` of a gas is:

At a power station, heat is removed from the heat exchanger by cooling water at `6.7xx10^9` J per minute. The cooling water enters at `6.0^o C` and leaves at `14.0^oC`. [ Take the specific heat capacity of water 4200 J/K`g^oC`]

Which of the following is the rate of water flow?

A light rod acted upon by three forces, is in equilibrium. Which of the following diagram shows the possible position and direction of the forces?

The weight indicated on a balance is X when a beaker of water is placed on it. A solid object has weight Y in air and displaces weight Z of water when completely immersed. The given diagram shows the object suspended from a light string and completely immersed in the beaker of water. What is the balance reading in the given arrangement?

The fundamental frequency of a sonometer wire of length `l` is `n_o`. A bridge is now introduced at a distance of `Delta l` (<<`l)`from the introduced of the wire. The lengths of wire on the sides of the bridges are now vibrated in their fundamental modes. Then, the beat frequency nearly is:

Two point masses M each are placed at (L, 0) & (-L, 0). A third point mass M is uniformly rotating on the circle `x^2+y^2=L^2`. Equation of path traced by COM of 3 point masses is

Two particles A and B are moving in XY plane. Particle A moves along a line with equation y=x while B moves along X axis such that their X coordinates are always equal. If B moves with a uniform speed 3 m/s, the speed of A is:

A train moving towards a hill at a speed of 72 km/hr sounds a whistle of frequency 500 Hz. A wind is blowing from the hill at a speed of 36 km/hr. If the speed of sound in air is 340 m/s, the frequency heard by a man on the hill (nearly) is:

If a section of a soap bubble of radius r by a plane through its centre is considered, the force on the half due to surface tension is:

The given diagram shows a detector placed between a transmitter of sound waves and a metal plate. At three adjacent points, R, S and T, the meter shows zero intensity. Which of the following is the frequency of the emitted wave?

(Take the velocity of sound as=300 m/s)

Air is pumped into a balloon, of initial volume V, until its diameter has double. If the atmospheric pressure is p, what is the work done against the atmosphere?

The given graph illustrates a transverse wave travelling on a string at a particular instant, and the points P, Q, R and S represent element of the string. Which of the following statements about the motion of the element of the correct?

The given diagram shows isotherms for a fixed mass of an ideal gas at temperature `T_1` and `T_2`. What is the value of the ratio

`(text(r.m.s. speed of the molecules at temperature) T_2)/(text(r.m.s. speed of the molecules at temperature) T_1)` ?

A spring hangs vertically from the ceiling and a mass is attached to its free end. When the mass is pulled down and released, it oscillates vertically with simple harmonic motion of period T. The variation with time t of its distance from the ceiling is as shown. Which statement gives a correct deduction from this graph?

The given diagram shows a straight length of tape being wound on to a reel. The reel is rotating about a fixed axis with constant angular velocity and its radius is increasing at a steady rate. Which graph correctly shows the variation with time of the speed v at which the tape moves towards the roll?

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