A 500W heater is used to heat 0.6kg of water from 25ºC to 100ºC in t\(_1\) seconds. If another 1000W heater is used to heat 0.2kg of water from 10ºC to 100ºC in t\(_2\), seconds, find \(\frac{t_1}{t_2}\)
A
50
B
5
C
5/4
D
1/5
Verified Correct Answer: B.
Physical Principles & Numerical Solution
Heat energy = Electrical energy
mc\(\theta\) = power x time
0.6 x c x (100 - 25) = 500 x t\(_1\)
and, 0.2 x c x (100 - 10) = 1000 x t\(_2\)
\(\frac {t_1}{t_2}\) = \(\frac{0.09}{0.018}\) = 5
Source: Myschool Past Questions Archive (Record #27630)