The only possibility of heat flow in a thermos flask is through its cork which is `75 cm^(2)` in area and 5 cm thick. Its thermal conductivity is `0.0075 cal//cm sec^(@)C`. How lolng will 500 g of ice at `0^(@)C` in thermos flask will is `40^(@)C` and latent heat of ise is `80 cala//g`

A small coil is positionaed so that its axis lies along the axis of a large bar agnet, as shown in the figure. The coil has a cross-sectional area of 0.40 cm^2 and contains 150 turns of wire. The average magnetic flux density B through the coil aries with the distance x between the face of the magnet and the plane of the coil as shown in the figure. The coil is 5.0 cm from the face of the magnet to determine the magnetic flux density in the coil.

A 100 turn rectangular coil ABCD (in XY plane) is hung from one arm of a balance Fig. EP 4.23 A mass 500 g is added to the other arm to balance the weight of the coil. A current 4.9 A passes through the coil and a constant magnetic field of 0.2 T acting inward (in xz plane) is switched on such that only arm CD of length 1 cm lies in the field. how much additional mass 'm' must be added to regain the balance?

A geyser heats water flowing at the rate of 3.0 litres per minute from 27 ^@C to 77 ^@C . If the geyser operates on a gas burner, what is the rate of consumption of the fuel if its heat of combustion is 4.0 xx 10^4 J//g ?

Stearic acid [CH_(3)(CH_(2))_(16)CO_(2)H] is a fatty acid the part of fat that stores most of the energy .1.0 g of Stearic acid was burnt in a bomb calorimeter . The bomb had capacity of 652 J//^(@)C . If the temperature of 500 g water rose from 25.0 to 39.3^(@)C how much heat is released when the stearic acid was burned? ["Given "C_(p)(H_(2)O)=4.18J//g^(@)c]

A solenoid 60 cm long and of radius 4.0 cm has 3 layers of windings of 300 turns each. A 2.0 cm long wire of mass 2.5 g lies inside the solenoid (near its centre) normal to its axis, both the wire and the axis of the solenoid are in the horizontal plane. The wire is connected through two leads parallel to the axis of the solenoid to an external battery which supplies a current of 6.0 A in the wire. What value of current (with appropriate sense of circulation) in the windings of the solenoid can support the weight of the wire? g = 9.8 m s^-2 .

A metal rod A of 25 cm length expands by 0.050 cm when its temprature is raised frmo 0^@C to 100^@C . Another rod B of a different metal of length 40 cm expands by 0.040 cm for the same rise in temperature. A third rod C of 50 cm length is made up of pieces of rods A and B placed end to end expands by 0.03 cm on heating from 0^@C to 50^@C . Find the lengths of each portion of the composite rod C.

A circular disc of radius 3 cm is being heated. Due to expansion, its radius increases at the rate of 0.05 cm/s . Find the rate at which its area is increasing when radius is 3.2 cm .

How many grams of silver could be plated out on a serving tray by elelctolysis of a solution containing silver in +1 oxidation state for a period of 8.0 hours at a current of 8.46 amperes? What is the area of the tray if the thickness of the silver plating is 0.0025 cm? density of silver is 10.5 g/cm^3 .