Question

A 12 V car battery is rated at 100 Ah (Ampere-hours). How many times could a 0.8 kW camping kettle be boiled, if it takes an average of 5 minutes to boil the kettle?

Answer 1

18 times

Step-by-step explanation:

We are given;

• Voltage of the car battery as 12 V
• Rating of the battery is 100 Ah
• Power of the kettle is 0.8 kW
• Time taken to boil the kettle is 5 watts

We are required to calculate the number of times the kettle can be boiled.

Step 1: Energy released by the battery

Energy = Voltage × Current × time

Voltage = 12 V

Current = 100 Amperes

Time - 1 hour or 3600 sec

Therefore;

Energy from the battery = 12 V × 100 A × 3600 sec

= 4,320,000 Joules

Step 2. Energy required to boil one kettle

Energy = Power × time

In this case;

Power is 0.8 kW or 800 watts

Time = 5 mins or 300 seconds

Therefore;

Energy required to boil a kettle

= 800 watts × 300 seconds

= 240,000 Joules

Step 3: Number of times the kettle that can be boiled.

We divide the total amount of energy from the battery by the energy needed to boil one kettle.

Number of times = 4,320,000 Joules ÷ 240,000 Joules

= 18 times

Therefore, the kettle can be boiled 18 times using energy from the battery.