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

Why is it difficult to cook on hills ?

Liquid oxygen at $50\  K$ is heated to $300\  K$ at constant pressure of $1\  atm$. The rate of heating is constant which of the following graphs represents the variation of temperature with time

A solid cube having certain fixed melting and boiling points takes heat from some source.The variation  of temperature $\theta$ of the cube with the heat supplied $Q$ is shown in the adjoining graph. The portion $BC$ of the graph represents the conversion of

The graph signifies