A device for heating a cup of water in a car connects to the car's battery, which has an emf EMF = 10.0 V and an internal resistance r_int = 0.08 \Omega. The heating element that is immersed in the cup of water is a resistive coil with resistance R.
David wants to experiment with the device, so he connects an ammeter into the circuit and measures10.5 A when the device is connected to the car's battery. From this, he calculates the time to boil a cup of water using the device. If the energy required is 100 kJ, how long does it take to boil a cup of water?