26. An electric kettle with negligible heat capacity is

Question

rated at 2000 W. If 2.0kg of water is put in it,
how long will it take the temperature of water to
rise from 200C to 1000C?
A. 420s
B. 336s
C. 168s
D. 84s.

Answer 1

To find the time it takes for the temperature to rise from 20°C to 100°C, we can use the formula:

Q = mcΔT

Where:
Q = heat transferred
m = mass of water
c = specific heat capacity of water
ΔT = change in temperature

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

First, we need to convert the mass of water from kg to grams:
2.0kg * 1000g/kg = 2000g

Next, we calculate the heat transferred:
Q = (2000g)(4.18 J/g°C)(80°C)
Q = 668,800 J

Now, we use the formula for power:
P = Q/t

Where:
P = power (in watts)
Q = heat transferred (in joules)
t = time (in seconds)

We rearrange the formula to solve for time:
t = Q/P

t = 668,800 J / 2000 W
t = 334.4 s

So, it will take approximately 334.4 seconds for the temperature to rise from 20°C to 100°C.

Since none of the answer choices match exactly, we can round to the nearest whole number, which would be 334 seconds.

Therefore, the closest answer choice is B. 336s.