This question integrates physics, mathematics, common sense of life, etc. Please read it carefully.
The picture shows an electric kettle commonly used in households. The mass of the electric kettle is measured to be 0.6kg, and its contact area with the table top is 0.02 square meters. The rated voltage of the electric kettle is 220V and the rated power is 1000W. [g is 10 N/kg, and the specific heat capacity of water is 4200J/(kg·℃)
1. Find the rating of the electric kettle Current (retain one decimal place)
rated current = rated power ÷ rated voltage
rated current = 1000÷220≈4.5A
2. Find the pressure of the electric kettle on the horizontal table top.
pressure=pressure÷contact area
pressure=mass×g=0.6×10=6N
pressure=6÷0.02=300Pa
3. Use this electric kettle to heat 1kg of water with an initial temperature of 20℃ At 100°C, how much heat does the water absorb at least?
heat change=specific heat capacity×mass×temperature difference
=4200×1×(100－20)
=336000J
4. When the electric kettle is working normally, if the heat loss is not considered, the mass in the pot is 1kg , How long does it take to heat water with an initial temperature of 20°C to 100°C.
The heat absorbed by the water is also the electric energy consumed
Knowing that the rated power of the kettle is 1000W, it means that the electric energy consumed per second is 1000J, and a total of 336000J of electric energy is consumed, so the time required is
336000÷1000 =336 seconds
I saw a sentence today, in our lives, we may not need this knowledge, who will have time to calculate these useless things, it is impossible to use the Pythagorean theorem, universal gravitation and other knowledge when buying food However, this knowledge determines whether we will buy or sell vegetables in the future.
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