All categories

1 year 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.

You might be interested in

Find the mass of a person walking west at a speed of 0.8 m/s with a momentum of 52.0 kg.m/s west.

KIM [24]

Answer:

mass of the person walking to west is 65 kg.

Given:

Momentum = 52 $\frac{kg m}{s}$

Speed = 0.8 $\frac{m}{s}$

To find:

Mass of the person = ?

Formula used:

Momentum is given by,

P = m × v

Where, P = momentum

m = mass

v = speed

Solution:

Momentum is given by,

P = m × v

Where, P = momentum

m = mass

v = speed

Mass = $\frac{P}{v}$

m = $\frac{52}{0.8}$

m = 65 kg

Thus, mass of the person walking to west is 65 kg.

5 0

1 year ago

susan drops her camara in the river from a bridge that is 250 feet high. How long does it take the camara to fall 250 feet?

Pavlova-9 [17]

It takes around 4 seconds for the camera ro fall 250 feet

use the quadratic formula where a=-16 b=0 and c=250

6 0

1 year ago

Match the measuring instrument with the appropriate statement.

yaroslaw [1]

<u>Answer:</u>

1A, 2E, 3C, 4F, 5B, 6D

<u>Explanation:</u>

Tilt meter is a an equipment used to measure very small changes from vertical level. So it is a correct match for blank space in statement A.

Richter Scale is a scale of measurement of earthquake strength, So it is a correct match for blank space in statement E.

Mercalli Intensity Scale measures effect of an earthquake, like damage caused.So it is a correct match for blank space in statement C.

Seismograph is earthquake wave measuring instrument. So it is a correct match for blank space in statement F.

Correlation Spectrometer (C.O.S.P.E.C.) is used to measure sulfur dioxide content in smoke. So it is a correct match for blank space in statement B.

Moment Magnitude Scale is an earthquake measuring scale for great earthquakes. So it is a correct match for blank space in statement D.

7 0

2 years ago

Paintball guns were originally developed to mark trees for logging. A forester aims his gun directly at a knothole in a tree tha

emmasim [6.3K]

Answer:

The distance between knothole and the paint ball is 0.483 m.

Explanation:

Given that,

Height = 4.0 m

Distance = 15 m

Speed = 50 m/s

The angle at which the forester aims his gun are,

$\tan\theta=\dfrac{4}{15}$

$\tan\theta=0.266$

$\cos\theta=\dfrac{15}{\sqrt{15^2+4^2}}$

$\cos\theta=0.966$

Using the equation of motion of the trajectory

The horizontal displacement of the paint ball is

$x=(u\cos\theta)t$

$t=\dfrac{x}{u\cos\theta}$

Using the equation of motion of the trajectory

The vertical displacement of the paint ball is

$y=u\sin\theta(t)-\dfrac{1}{2}gt^2$

$y=u\sin\theta(\dfrac{x}{u\cos\theta})-\dfrac{1}{2}g(\dfrac{x}{u\cos\theta})^2$

$y=x\tan\theta-\dfrac{gx^3}{2u^2(\cos\theta)^2}$

Put the value into the formula

$y=(15\times0.266)-(\dfrac{9.8\times(15)^2}{2\times(50)^2\times(0.966)^2})$

$y=3.517\ m$

We need to calculate the distance between knothole and the paint ball

$d=h-y$

$d=4-3.517$

$d=0.483\ m$

Hence, The distance between knothole and the paint ball is 0.483 m.

8 0

2 years ago

You catch a volleyball (mass 0.270 kg) that is moving downward at 7.50 m/s. In stopping the ball, your hands and the volleyball

sesenic [268]

Explanation:

The work done equals the change in energy.

W = ΔKE

W = 0 − ½mv²

W = -½ (0.270 kg) (-7.50 m/s)²

W = -7.59 J

Work is force times displacement.

W = Fd

-7.59 J = F (-0.150 m)

F = 50.6 N

3 0

2 years ago