The rated power of an electric rice cooker is 800W. It is known that cooking rice requires 4.8x10 quintic joules of heat. If the electric rice cooker does not consider the loss of energy during normal operation, how long does it take to cook rice with it?

The rated power of an electric rice cooker is 800W. It is known that cooking rice requires 4.8x10 quintic joules of heat. If the electric rice cooker does not consider the loss of energy during normal operation, how long does it take to cook rice with it?

Q suction = 4.8 × 10 ^ 5J
If the heat loss is not taken into account, then q discharge = q suction = 4.8 × 10 ^ 5J
Q = Pt, t = q / P = 4.8 × 10 ^ 5 / 800 = 6000s = 100min
A: slightly

There are 22 classrooms in the teaching building of a junior middle school. Each classroom has 24 40W fluorescent lamps, one 100W color TV and one 1.2kW water dispenser
Turn on all the above electrical appliances and power them on for 10 hours every day. How many kilowatts of electricity will be consumed in a month (30 days)?

The unit of power is kilowatt and the unit of time is hour
W=Pt=(0.04kw*24*+0.1kw+1.2kw)*22*(10h*30)=1491.6kw.h
About 1491.6 kwh is consumed

There are two 100W incandescent lamps, five 60W incandescent lamps, ten 40W fluorescent lamps, one 1000W air conditioner, one 120W color TV and one 120W refrigerator in a family circuit. The rated current of the fuse is 11a (1) what is the maximum normal working current in the circuit? (2) when all the electrical appliances in the circuit are working normally, Will the fuse be burnt out? (3) when all the electrical appliances in the circuit are working normally, if a person with a resistance of 2.2 kiloohm accidentally has a single wire electric shock, how many amperes is the current passing through the human body? Do you need to replace the fuse with a higher rated current? Why?

1, according to P = UI, I = (100 * 2 + 60 * 5 + 40 * 10 + 1000 + 120 + 120) / 220 = 9.73a
The maximum current is 9.73a,
2,9.73

There are eight lamps in the office of grade seven in the school, including two kinds of 40W and 100W. It is known that the total wattage of these eight lamps is 500W, so how many lamps are there in 40W and 100W
Solution of linear equation with one variable

Suppose that 40W has x, then 100W has (8-x)
40X+100（8-X）=500
40X+800-100X=500
800-60X=500
60X=300
X=5
8-X=8-5=3