Tag: physics

${l _2} = {l _1}\left( {1 + {\alpha _A}\Delta T} \right)$

${l _2} = {l _1} + {l _1}{\alpha _A}\Delta T$

$\displaystyle {{{l _2} - {l _1}} \over {{l _1}}} = {\alpha _A}\Delta T$

$\displaystyle {{0.01 \times {{10}^{ - 2}}} \over {1 \times {{10}^{ - 2}} \times 25 \times {{10}^{ - 6}}}} = \Delta T$

$\Delta T = {40^0}C$

1 calorie: The amount of energy required to warm $1\ g$ of air-free water from $14.5^oC\ to\ 15.5^oC$ at a constant pressure of $101.325\ kPa$ $(1 atm)$

Answer is (A).

The S.T. unit of heat capacity is heat required per degree rise in temperature. So it is $JK^{-1}$

1 cal = 4.18 joules

The SI unit for energy, including heat energy, is the joule.

The therm (symbol, thm) is a non-SI unit of heat energy equal to100000 British thermal units (Btu). It is approximately the energy equivalent of burning 100 cubic feet (2.83 cubic metres) – often referred to as 1 CCF – of natural gas.

The amount of heat required to raise the temperature of one gram of water  through $ 1 ^{o}$ (from $14.5^{o}C$ to $15.5^{o}C$), is called one calorie.

The amount of heat energy required to raise the temperature of 1 g water by $1^o\ C$ is called one calorie.