If two balls of the same metal weighing $5\, g$ and $10\, g$ strike a target with the same velocity,and the heat energy developed is used solely for raising their temperature,then the temperature rise will be higher:

Which form of heat was believed in before the modern time?

$A$ block of ice at temperature $-20^{\circ} C$ is slowly heated and converted to steam at $100^{\circ} C$. Which of the following diagrams is most appropriate?

$A$ drilling machine of $10 \, kW$ power is used to drill a bore in a small aluminium block of mass $8 \, kg$. If $50 \%$ of power is used up in heating the machine itself or lost to the surroundings,then the rise in temperature of the block in $2.5 \, minutes$ is ........ $^\circ C$. [Specific heat of aluminium $= 0.91 \, J/g \cdot ^\circ C$]

$A$ bullet of mass $5\, g$,travelling with a speed of $210\, m/s$,strikes a fixed wooden target. One half of its kinetic energy is converted into heat in the bullet while the other half is converted into heat in the wood. The rise of temperature of the bullet if the specific heat of its material is $0.030\, cal/(g \cdot ^{\circ}C)$ $(1\, cal = 4.2 \times 10^{7}\, ergs)$ is close to $.......^{\circ}C$.

$A$ thermocouple develops $40\,\mu V/K$. If the hot and cold junctions are at $40\,^{\circ}C$ and $20\,^{\circ}C$ respectively,then the emf developed by a thermopile using $150$ such thermocouples in series shall be ............... $mV$.