How long does it take a 750 W heater operating at full rating to raise the temperature of 1 kg of water from 40oC to 70oC? (Take the specific heat capacity of water as 4200 J kg-1 K-1 and neglect heat losses).
-
A.
84s -
B.
112s -
C.
168s -
D.
280s -
E.
616s
Correct Answer: Option C
Explanation
div class=”eq-c”>pt = mcθΔ; t =
mcθΔp
=
1 x 4200 x (70 – 40)750
= 168s