A leadpiece of mass 25g gives out 1200 calories of heat when it is cooled from `90^(@)`C to `10^(@)` C . What is its i) Specific heat ii) thermal capacity and ii) Water equivalent.

Explanation

Mass of lead piece (m) = 25 g = 0.025 kg Amount of heat given out= 1200 calories Amount of heat energy given out
`(dQ) = 1200 xx 4.2 `J
The fall in temperature dT) =` (90 10)^(0) C = 80^(0) C ` = 80 K
(i) Specific heat S = `(1)/(m) (dQ)/(dT) = (1)/(0.025) xx (1200 xx 4.2)/(80)`
= `(5040)/(2) = 2520J " kg"^(-1) K^(-1)`
(ii) Thermal capacity= ms = `0.025 xx 2520 = 63 j K^(-1)`
(iii) Water equivalent = W = `(63)/(4200)` kg