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3 years ago

a water heater has a power rating of 1 kW. how many seconds will this heater take to boil 1 liter of water?

1 answer:

5 0

Answer:
4.65 minutes.

Explanation:
Theoretical Assumptions (not realistic): 1) ALL of the heat energy is transferred to the water, and 2)the water is uniformly heated. 3) The water density is 1.0g/mL.
Because we are only heating it TO the “boiling point”, ONLY the energy to heat the water from 20 to 100’C using the heat capacity or specific heat of water is required. A “Watt” is 1 Joule/second. The specific heat of water is 4.184 J/g-’C. Water mass is 1000g. The energy required to heat it is therefore
1000
g
⋅
4.184
(
J
g
’
C
)
⋅
(
100
−
20
)
’
C
=
334720
J

The heater supplies 1200 J/s, so the time to provide this heat to the water is
334720
J
1200
(
J
s
)
=
278.9
s
or 4.65 minutes.

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A uniform rod of length 50cm and mass 0.2kg is placed on a fulcrum at a distance of 40cm from the left end of the rod. At what d

oksano4ka [1.4K]

Answer:

x = 45 cm

Explanation:

Given that,

The length of a rod, L = 50 cm

Mass, m₁ = 0.2 kg

It is at 40cm from the left end of the rod.

We need to find the distance from the left end of the rod should a 0.6kg mass be hung to balance the rod.

The centre of mass of the rod is at 25 cm.

Taking moments of both masses such that,

$15\times 0.2=x\times 0.6\\\\x=\drac{3}{0.6}\\\\x=5\ cm$

The distance from the left end is 40+5 = 45 cm.

Hence, at a distance of 45 cm from the left end it will balance the rod.

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3 years ago

What occurs during stage one sleep

Mekhanik [1.2K]

Answer:

Stage one of sleep, also known as the transitional phase, occurs when one finds themselves floating in and out of consciousness. During this NREM stage, you may be partially awake while your mind begins to drift off. This period of drowsiness eventually leads to a light sleep

Explanation:

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3 years ago

An airplane starts from rest at the end of a runway and accelerates at a constant rate. In the first second, the airplane travel

Licemer1 [7]

Answer:

$v=4.44\frac{m}{s}$

Explanation:

Given that the airplane starts from the rest (this is initial velocity equals to zero) and accelerates at a constant rate, position can be described like this: $x=v_{0}t +\frac{1}{2} at^{2}$ where x is the position, t is the time a is the acceleration and $v_{0}$ is initial velocity. In this way acceleration can be found. $a=\frac{2(x-v_{0}t) }{t^{2} } =\frac{2(1.11m-0)}{1s^{2} } =2.22\frac{m}{s^{2} }$ .

Now we are able to found velocity at any time with the formula: $v=v_{0} +at = 0\frac{m}{s} +(2.22\frac{m}{s^{2}}.2s)=4.44\frac{m}{s}$

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3 years ago

Windows having double glass panes with some space between them is called double glazing. Why do windows in cold countries have d

ValentinkaMS [17]

Answer: for insulation of heat

Explanation:

Windows in cold countries have double glazing windows to provide a barrier against the outside temperature by creating a buffer zone between two glasses.

The air or any other gas-filled between the glasses act as an insulator and offer great resistance to outside temperature thereby maintaining the inside temperature intact.

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2 years ago

What occurs when the pitch increases and the sound source is in motion? explain your answer.

Hoochie [10]

If you're listening to a sound that has a steady pitch, and suddenly the
pitch goes up, then you know that two things could have happened:

EITHER ...

-- The person or other source making the sound could have
raised the pitch of the sound being produced.

OR ...

-- The person or other source making the sound could have
started moving toward you.

OR ...

-- both.

Even if the pitch of the sound leaving the source doesn't change,
you would still hear it increase if the source starts moving toward
you. That's the so-called "Doppler effect".

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3 years ago