When an electric kettle containing cold water is switched on, the water in it starts boiling after a few minutes. what is the source of the heat energy of the boiling water?
mechanical energy from the power socket
newly created energy that increased the total energy
mechanical energy from the heating element in the kettle
already existing energy that was present in some other form

Newly created energy that increased the total energy

Explanation:

The energy existed before, but not in the system, it is entering the system as soon as you turn on the kettle this means that the kettle is experimenting an electric current on the resistance that has touching the water, this electric energy is being converted into heat energy and heating up the water in the kettle.

It is transformed into electrical energy.

Explanation:

while cooking a piece of 1/2 pound beef steak, a cast iron pan (2.4kg in weight) was heated 260 celsius.

a pan containing water is placed in a positio n where it is exposed to a 10 mile per hour wind. the pan contains a uniform depth of 1.27 cm of water, is quite wide, and has a length of 2.44 m in the wind direction. the water in the pan is at a constant temperature of 15.5 °c.