JAMB - Physics (1991 - No. 16)
How long does it take a 750W heater to raise the temperature of 1kg of water from 20oC to 50oC [specific heat capacity of water = 4200Jkg-1K-1]
84s
112s
168s
280s
Vysvětlení
Heat energy = Elect. energy
mc\(\theta\) = power x time
1 x 4200 x (50 - 20) = 750 x t
t = 168s
mc\(\theta\) = power x time
1 x 4200 x (50 - 20) = 750 x t
t = 168s