JAMB - Physics (1995 - No. 16)
An electric kettle with negligible heat capacity is rated at 2000W. If 2.0kg of water is put in it, how long will it take the temperature of water to rise from 20OC to 100OC? [specific heat capacity of water = 4200Jkg-1k-1]
420S
336S
168S
48S
Vysvětlení
Heat energy = Elect. energy
mc\(\theta\) = power x time
2 x 4200 x (100 - 20) = 2000 x t
t = 336s
mc\(\theta\) = power x time
2 x 4200 x (100 - 20) = 2000 x t
t = 336s