Recent questions and answers in physics

The given diagram shows three light pieces of paper placed on a wire that is stretched over two supports, Q and R, a distance 4x apart. When the wire is made to vibrate at a particular frequency, all the pieces of paper, except the middle one, fall off the wire. Which of the following could be the wavelength of the vibration?

At temperatures close to 0 K, the heat capacity C of a certain solid is related to its temperature T by the equation `C=aT^3`, where a is a constant characteristic of the solid. Heat is supplied to the solid at a steady rate. Which graph best represents the variation of its temperature T with time t?

A small steel sphere of mass m is falling vertically through a viscous liquid with a constant speed v. Which row in the table correctly describes the changes with time in the kinetic energy and gravitational potential energy of the sphere?

	Kinetic Energy	Gravitational Potential Energy
(A)	constant and equal to `1/2 mv^2`	decreases at a rate of mgv
(B)	constant and equal to `1/2 mv^2`	decreases at a rate of `(mgv-1/2 mv^2)`
(C)	increase at a rate of mgv	decreases at a rate of mgv
(D)	increase at a rate of mgv	decrease at a rate of `(1/2 mv^2-mgv)`

A steel ball is released from rest a distance above a rigid horizontal surface and bounces several time. The diagram shows how its velocity varies with time. Which statement correctly explains why the areas X and Y are equal?

Standing waves are generated on a sonometer string loaded with a cylindrical body. If the cylinder is completely immersed in water, the length of the loops changes by a factor of 2.2. The specific gravity of the material of the cylinder is:

Three rods of identical cross-sectional area and made from the same metal from the sides of an isosceles triangle ABC, right angled at B. The points A and B are maintained at temperatures T and `(sqrt2) T` respectively. In the steady state, the temperature of the point C is `T_c`. Assuming that only heat conduction takes place,` T_c/T` is

Two identical containers A and B with frictionless pistons contain the same ideal gas at the same temperature and the same volume V. The mass of the gas in A is `m_A` and that in B is `m_B`. The gas in each cylinder is now allowed to expand isothermally to the same final volume 2V. The changes in the pressure in A and B are found to be `Delta p` and `1.5 Delta p` respectively. Then

Starting with the same initial conditions, an ideal gas expands from volume `V_1` to `V_2` in three different ways, the work done by the gas is `W_1` if the process is purely isothermal, `W_2` if purely isobaric and `W_3` if purely adiabatic, then

Three rods made of the same material and having the same cross-section have been joined as shown in the figure. Each rod is of the same length. The left and right ends are kept at `0^o C `and `90^o C` respectively. The temperature of junction of the three rods will be

An ideal gas is taken through the cycle `A -> B -> C -> A`, as shown in the figure. If the net heat supplied to the gas in the cycle is 5J, the work done by the gas in the process `C ->`A is

Which of the following graphs correctly represent the variation `beta=-((dV)/(dp))/V` with p for an ideal gas at constant temperature?

An ideal gas is initially at temperature T and volume v. Its volume is increased by `Delta V` due to an increase in temperature `Delta T`, pressure remaining constant. The quantity `delta= (Delta V)/( V Delta T)` varies with temperature as

Two metallic spheres `S_1` and `S_2` are made of the same material and have got identical surface finish. The mass of `S_1` is thrice that of `S_2`. Both the spheres are heated to the same high temperature and placed in the same room having lower, temperature but are thermally insulted from each other. The ratio of the initial rate of cooling of `S_1` to that of `S_2` is

When an ideal diatomic gas is heated at constant pressure the fraction of the heat energy supplied which increases the internal energy of the gas is

An ideal gas is taken through a cyclic thermodynamical process through four steps. The amounts of heat involved in these steps are `Q_1=5960` J, `Q_2=-5585` J, `Q_3=-2980` J, `Q_4=3645` J, respectively. The corresponding works involved are `W_1 =2200J, W_2=-825` J, `W_3=-1100` J and `W_4` respectively. The value of `W_4` is

Argon and oxygen are both compressed adiabatically from the same initial pressure and volume `(P_1, V_1)` to same final pressure `P_2` and volume `V_2`. The work done will be

A certain quantity of heat when supplied to a monoatomic gas constant volume raises it temperature by `20^oC`, If the same amount of heat is supplied at constant pressure the increment in temperature would have been

The isothermal Bulk modulus of an ideal gas at pressure 'P' is

70 calories of heat are required to raise the temperature of two moles of an ideal gas at constant pressure from `30^oC` to `35^oC`. The amount of heat required (in calories) to raise the temperature of the same gas through the same range `(30^oC` to `35^oC)` at constant volume is

In a thermodynamic process pressure of a fixed mass of a gas is changed in such a manner that the gas releases 20 J of heat when 8 J of work was done on the gas. If the initial internal energy of the gas 30 J, then the final internal energy will be

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