An iron smaple having mass 8.4 kg is repeatedly taken over cycles of magnetisation and demagnetisation at a frequency of 50Hz. It is found that energy of 3.2 J is dissipated as heat in the sample in 30 minutes. If the denstiy of iron is `7200 kg m^-3`, calculate the value of energy dissipated per unit volume per cycle in the iron sample.

A transformer is working on 220V.50 Hz a.c. supply. The iron core of the transformer has a mass of 8.4 kg.. From the plot of B-H loop for the core, it is found that area of hte loop is 480 J m^-3 . If the density of iron is 7,500 kgm^-3 , find the loss of energy in the core of transformer in 1 hour.

They hysteresis loss for a speciment of iron weighing 12 kg is equivalent to 300 J m^-3 cyc^-1 . Find the loss of energy per hour at 50 cycles s^-1 . Given, density of iron = 7,500 kg m^-3

One end of a long string of linear mass density 8.0 xx 10^-3 kg m^-1 is connected to an electrically driven tuning fork of frequency 256 Hz. The other end passes over a pulley and is tied to a pan containing a mass of 90 kg. The pulley end absorbs all the incoming energy so that reflected waves at this end have negligible amplitude. At t= 0, the left end (fork end) of the string x = 0 has zero transverse displacement (y = 0) and is moving along positive y-direction. The amplitude of the wave is 5.0 cm. Write down the transverse displacement y asfunction of x and tthat describes the wave on the string

A person trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the massis dissipated:- Fat supplies 3.8 xx 10^7J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?

A wire of mass 9.8*10^(-3) kg per metre passes over a friction less pulley fixed on the top of an inclined friction less plane which makes an angle of 30^@ with the horizontal. Masses M_(1) and M_(2) are tied at the two end of the wire. The mass M_(1) rests on the plane and the mass M_(2) hangs vertically downward. The whole system is in equilibrium. Now a transverse wave propagates along the wire with a velocity of 100ms^(-1) . Find the values of masses M_(1) and M_(2) . Take g= 9.8ms^(-2) .

Calculate the number of millilitre of NH_3 (aq) solution (d=0.986 g/mL) contain 2.5% by mass NH_3 , which will be required to precipitate iron as Fe(OH)_3 in a 0.8g sample that contains 50% Fe_2O_3 .

A current of 2.4 A flows through a wire of cross-sectional area 1.5 mm^2 . Find the current density in the wire. If the wire contains 8 xx 10^28m^-3 elecrtrons per unit volume calculate the average relaxation on time. Given that charge on electron = 1.6 xx 10^-19C and mass of electron =9.1 xx 10^-31 kg.