A Carnot's heat engine works between the temperature $$527^{\circ} \mathrm{C}$$ and $$127^{\circ} \mathrm{C}$$. What amount of heat should it consume per second to deliver mechanical work at the rate of $$1.0 \mathrm{~kW}$$ ?
The total energy of an electron in the second excited state of hydrogen atom is about $$-1.51 \mathrm{~eV}$$. Its kinetic energy in this state is
The masses of block $$A$$ and $$B$$ are $$m$$ and $$M$$, respectively. Between $$A$$ and $$B$$, there is a constant frictional force $$F$$ and $$B$$ can slide on a smooth horizontal surface. A is set in motion with velocity $$3 v_0$$ while $$B$$ is at rest. What is the distance moved by $$A$$ relative to $$B$$ before they move with the same velocity?
Magnetic moment of bar magnet is $$2 M$$. The work done to turn the magnet by $$90^{\circ}$$ of magnet in direction of magnetic field $$B / 2$$ will be