Two holes of unequal diameters $d_1$ and $d_2\, (d_1 > d_2)$ are cut in a metal sheet. If the sheet is heated

A coffee maker makes coffee by passing steam through a mixture of coffee powder, milk and water. If the steam is mixed at the rate of $50 \,g$ per minute in a mug containing $500 \,g$ of mixture, then it takes about $t_0$ seconds to make coffee at $70^{\circ} C$ when the initial temperature of the mixture is $25^{\circ} C$. The value of $t_0$ is close to .......... $s$ (ratio of latent heat of evaporation to specific heat of water is $540^{\circ} C$ and specific heat of the mixture can be taken to be the same as that of water)

Steam at $100\,^oC$ is passed into $22\,g$ of water at $20\,^oC$  The mass of water that will be present when the water acquires a temperature of $90\,^oC$  (Latent heat of steam is $540\,cal/g$) is ......... $\mathrm{g}$

A lead bullet at $27\ ^oC$ just melts when stooped by an obstacle. Assuming that $25\%$ of heat is absorbed by the obstacle, then the velocity of the bullet at the time of striking  ....... $m/s$  ( $M.P.$ of lead $= 327\,^oC$ , specific heat of lead $= 0.03\,cal/g\,^oC$ , latent heat of fusion of lead $= 6\,cal/g$ and $J = 4.2\,joule/cal$ )

Water is used to cool radiators of engines in car because

If the volume of a block of metal changes by $0.12\%$ when it is heated thrugh $20\,^oC$, the coefficient of linear expansion (in $^o{C^{ - 1}}$) of the metal is