>>1290868A 1500W kettle is much slower to boil a cup of water than a 2400W kettle.
The specific heat of water is 4.2, which means that 4.2J of energy is required to heat 1mL of water by 1C.
To heat 1mL of water from 18C to 100C requires 344.4J
1 cup of water is 250mL so to boil one cup takes 86.1KJ
1J = 1W/s.
Assuming no resistance and energy loss:
A 1500W kettle delivers 1.5KJ/s, which means it takes 57.4s to boil a cup of water.
A 2400W kettle delivers 2.4KJ/s, which means it takes 35.9s to boil a cup of water.
