Question

Помогите!!! электрокипятильник с сопротивлением спирали R=140 Ом опустили в банку с водой и включили в сеть напряжением U=220 В. Объем воды V=3,0 л и температура t=18 градусов. Через промежуток времени =1.0 ч кипятильник выключили. Определите массу воды в банке после выключения кипятильника. Потерями энергии принебречь

Answer 1

Кипятильник отдал воде Q1 количества теплоты.Q1=tU²/R=1244,6кДжДля того чтобы нагреть воду до темп кипения нужно Q2 количества теплотыQ2=cpV(t2-t1)=1033,2кДжQ1-Q2 количество теплоты ушедшее на парообразование.Q1-Q2=211,4кДж-----211,4кДж=Фm где Ф - удельная теплота парообразованияm=211,4/2256=94гр----M=pV-m=1000*0,003-0,094=2,906кг

Answer 2

Calculation of the Mass of Water in the Container

To determine the mass of water in the container after the electric kettle is turned off, we need to consider the initial conditions and the energy transferred to the water.

Given: - Resistance of the heating element (spiral): R = 140 Ω- Voltage applied to the kettle: U = 220 V- Volume of water in the container: V = 3.0 L - Initial temperature of the water: t = 18°C - Time interval during which the kettle is on: Δt = 1.0 h

To calculate the mass of water, we can use the formula:

Q = I^2 * R * Δt

where: - Q is the heat energy transferred to the water - I is the current flowing through the heating element

To find the current, we can use Ohm's law:

I = U / R

Substituting the given values:

I = 220 V / 140 Ω = 1.57 A

Now we can calculate the heat energy transferred to the water:

Q = (1.57 A)^2 * 140 Ω * 1.0 h

Simplifying the equation:

Q = 1.57^2 * 140 * 1.0 J

Next, we need to calculate the change in temperature of the water using the specific heat capacity formula:

Q = m * c * Δt

where: - m is the mass of water - c is the specific heat capacity of water - Δt is the change in temperature

The specific heat capacity of water is approximately 4.18 J/g°C.

Rearranging the equation:

m = Q / (c * Δt)

Substituting the given values:

m = (1.57^2 * 140 * 1.0) / (4.18 * (1000 * 3.0) * (100 - 18)) g

Simplifying the equation:

m = 0.000014 g

Therefore, the mass of water in the container after the electric kettle is turned off is approximately 0.000014 g.

Please note that this calculation assumes no energy losses and neglects the heat capacity of the container itself.