You are at home during a storm when a downed tree interrupts your house's electricity supply. The power company tells you it will be 9.5 hours until it's repaired. Thinking quickly, you decide to head out and buy ice to keep the fridge cold at T=0∘C.
Before leaving home, you look up the thermal resistance of the refrigerator's walls to be 0.24 K/W.
Calculate the mass of ice you should buy if the room temperature is always 20 ∘C.
Hint: the specific heat of water is 4184 J kg−1 K−1 and the latent heat of fusion for water is 334 k
Answers
To keep the fridge cold for 9.5 hours, you should buy approximately 0.249 kg (or 249 grams) of ice, considering the thermal resistance of the refrigerator's walls and the temperature difference between the room and the fridge.
First, let's calculate the heat transfer through the refrigerator's walls over the duration of 9.5 hours. We can use the formula:
Q = ΔT / R
where Q is the heat transfer, ΔT is the temperature difference, and R is the thermal resistance.
Given that the room temperature is 20 °C and the fridge temperature is 0 °C, the temperature difference is ΔT = 20 °C - 0 °C
= 20 °C.
Plugging in the values, we get:
Q = 20 °C / (0.24 K/W)
= 83.33 W
The heat transfer represents the amount of heat that needs to be absorbed by the ice to keep the fridge cold.
Now, let's calculate the amount of heat required to convert the ice at 0 °C into water at 0 °C. This can be calculated using the latent heat of fusion, which is the amount of heat required to change the phase of a substance without changing its temperature.
The latent heat of fusion for water is 334 kJ/kg.
To convert it to joules, we multiply by 1000:
Latent heat of fusion = 334 kJ/kg
= 334,000 J/kg
Since the ice is at 0 °C and needs to be converted into water at 0 °C, there is no change in temperature. Therefore, the heat required is equal to the latent heat of fusion.
Now, let's calculate the mass of ice needed. We can use the formula:
Q = m * Latent heat of fusion
Rearranging the formula, we get:
m = Q / Latent heat of fusion
Substituting the values, we have:
m = 83.33 W / 334,000 J/kg
Calculating the result:
m ≈ 0.249 kg
Therefore, you should buy approximately 0.249 kg (or 249 grams) of ice to keep the fridge cold for 9.5 hours.
To keep the fridge cold for 9.5 hours, you should buy approximately 0.249 kg (or 249 grams) of ice, considering the thermal resistance of the refrigerator's walls and the temperature difference between the room and the fridge.
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Related Questions
a ball attached to a string is whirled in a horizontal circle such that it moves with constant speed. does the velocity of the ball change in this process? is the acceleration equal to zero? explain.
Answers
The velocity of the ball does not change in this process because it is moving in a circle at a constant speed. However, the acceleration of the ball is not equal to zero because it is constantly changing its direction.
The acceleration is the rate of change of velocity, and since the ball is changing direction, its velocity must also be changing. This acceleration is known as centripetal acceleration, and it is directed towards the centre of the circle.
This acceleration is necessary to keep the ball travelling in a circle because if it was not there, the ball would travel in a straight line away from the circle. The magnitude of this acceleration is equal to the square of the speed of the ball divided by the radius of the circle.
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Match the type of boundary with it's characteristic
Answers
Answer:
Transform= not destroyed or created
Divergent= crust created
Convergent= crust destroyed
Explanation:
The plates move in the opposite or away from each other at a transforming plate boundary. The two platform borders are not produced or destroyed in this case. As both plates converge on each other and thus destroy the plates for converging plate boundaries. When the plate is divergent, both plates shift away from each other by opening up and solidification for a new crust.
Answer:
Transform= not destroyed or created
Divergent= crust created
Convergent= crust destroyed
Explanation:
3. Use the simulation to predict where you think the magnet’s magnetic field was
strongest. Explain your answer.
Answers
Magnetic field is stronger at the poles whereas weaker at the center.
The magnetic field on the bar magnet is strongest at the poles because the field lines are most concentrated at the poles while on the other hand, the magnetic field is weaker in the central part of magnet.
Magnetic field has equal amount of strength at both the poles so in my opinion as well as scientific point of view, magnet field is stronger at the poles and weaker at the center of magnet.
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let's say you use a heat pump to pump heat from room a to room b. the temperature in room a is 18.6 oc and in room b is 27.3 oc. if your goal is to cool space a, what is the theoretical cop limit?
Answers
The theoretical Coefficient of Performance (COP) to cool the room A is 33.52.
Temperature in room A = T₁ = 18.6 oc
Temperature in room B = T₂ = 27.3 oc
To convert temperatures in Kelvin,
= T₁ = 18.6 + 273 =
= T₁ = 291.6 K
and,
= T₂ = 27.3 + 273
= T₂ = 300.3 K
The COP value to cool room A =
= COP = T₁ / (T₂ - T₁)
= COP = 291.6 / (300.3 - 291.6 )
= COP = 291.6 / 8.7
= COP = 33.52
The theoretical coefficient of performance to cool room A is 33.52 when the temperature of room A is 18.6 oc and that of room B is 27.3 oc.
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Which of the following best describes a situation in which the acceleration would be negative?
Group of answer choices
object speeds up
object stops
object slows down
object reverses
Answers
Answer:
object stop
Explanation:
How does the compass react to being away from the magnetic bar?
Answers
Answer:
When you take the compass away from the bar magnet, it again points north. So, we can conclude that the north end of a compass is attracted to the south end of a magnet. ... In Experiment 2, when you move the north pole of a magnet toward the south pole of the other magnet, the two magnets attract.
The moon Umbriel orbits Uranus (mass = 8.68 x 1025 kg) at a distance of 2.66 x 108 m. What is Umbriel's orbital speed?
Answers
Answer:
the orbital speed of umbriel is 16,800 km/h
Explanation:
The computation of the orbital speed is shown below
According to the question the Data provided in the question
Uranus mass = 8.68 × 10^25 kg
Distance = 2.66 × 10^8 m
Based on the above information, the orbital speed of Umbriel is
\(V = \sqrt{\frac{GM}{R} } \\\\ = \sqrt{\frac{((6.673e-11)(8.68e25)}{2.66e8} }\)
V = 4666 m/s
= 16,800 km/h
Hence, the orbital speed of umbriel is 16,800 km/h
Therefore it can be calculated by applying the above formula
Answer: 4665
Explanation: I got it right after on acellus
In a typical RC circuit, consisting of a DC source, a resistor, a capacitor, and a switch, the switch is closed at time t = 0. At that instant in time, capacitor behaves as a(n) ["open circuit", "short circuit"]. After a long time passes, capacitor behaves as a(n) ["open circuit", "short circuit"]
1) Select Open or Short Circuit for each of the following.
Answers
When the switch is closed at time t = 0 in a typical RC circuit:
1) At that instant in time, the capacitor behaves as a "short circuit". This is because a capacitor initially has no charge and acts as a conductor, allowing current to flow freely.
After a long time passes in the circuit:
2) The capacitor behaves as an "open circuit". This is because, over time, the capacitor charges up and reaches its maximum voltage. Once the capacitor is fully charged, it blocks the flow of direct current (DC), effectively acting as an open circuit. In this state, the capacitor does not allow any significant current to pass through it.
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Cadmium has eight naturally occurring isotopes. What do the isotopes have in common?
A.
atomic mass
B.
mass number
C.
number of protons
D.
number of neutrons
Answers
The isotopes of any element have same number of protons inside them.
What is Cadmium?Cadmium is a chemical element with the symbol Cd and atomic number 48. It is soft, silvery and white metal.
Given is about Cadmium that it has eight naturally occurring isotopes.
Isotopes are the atoms of the same element which have same number of protons in them but the number of neutrons are different. Isotopes usually have same chemical properties, but they have different physical properties. Their can be stable and unstable isotopes. These unstable isotopes are also called radioisotopes, since they emit radiation. Thus, the isotopes have same number of protons.
Therefore, the isotopes of any element have same number of protons inside them.
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i am a way of intentionally changing a genetic sequence in DNA so that a particular trait is produced what am i
Answers
I think that is the answer but don’t hold me to it. I actually think that there’s another name but I can’t think of it right now but I hope u get the right answer and a good grade
According to the law of conservation of energy, which statement must be
true?
O A. Energy that is transformed is neither destroyed nor created.
B. The total energy in a system can only increase over time.
C. There is only one form of energy.
D. Energy can change only from nuclear to chemical.
SUBMIT
Answers
Answer:
the answer is A
Explanation:
This means that a system always has the same amount of energy
The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside
if the density of wood is 0.5g/cm3 what is the mass of 1cm3
Answers
Answer:
O. 5 g
Explanation:
It literally says for every cm3 its 0.5 g
Re word this paragraph; so Its 'put in my own words' try to mix up the places of each sentences too please!
-
The sun creates three different types of electromagnetic radiation, which is considered harmful to humans. The light created includes X-rays, gamma rays, and ultraviolet light. These rays are harmful because of their high energy values, which are caused by their large frequencies. The gases of Earth's atmosphere absorb the high energy radiation, causing their molecules to move faster, but none of the light radiation reaches Earth's surface. Luckily for us, the high frequency of gamma rays and X-rays, as well as most ultraviolet light, cannot penetrate Earth's atmosphere and does not reach Earth's surface. If those harmful rays did reach Earth's surface it would make the planet plain to earth's
-
Answers
Answer:
here you go -
Explanation:
try using the paraphrasing tool website!
The sun makes three unique sorts of electromagnetic radiation, which is considered hurtful to people. The light made incorporates X-beams, gamma beams, and bright light. These beams are unsafe as a result of their high energy esteems, which are brought about by their enormous frequencies. The gases of Earth's air assimilate the high energy radiation, making their atoms move quicker, yet none of the light radiation arrives at Earth's surface. Fortunately for us, the high recurrence of gamma beams and X-beams, also as most bright light, can't enter Earth's environment and doesn't arrive at Earth's surface. In the event that those hurtful beams arrived at Earth's surface it would make the planet plain to earth's
All of the following are job duties an industrial/organizational psychologist may perform except
A. increasing job productivity
B. creating business products
C. improving business processes
D. consulting management
Answers
Answer:
B. creating business products
Explanation:
All of the following are job duties an industrial/organizational psychologist may perform except B. creating business products
The creation of business products is the one task that an industrial/organizational psychologist cannot accomplish, hence option B is the appropriate response.
What is psychology?Psychology is the name given to the scientific study of the mind and behavior. Psychiatrists are engaged in an ongoing study to better understand the mind, brain, and personality.
the psychological schools of thought known as biological, psychodynamic, behavioral, cognitive, and humanistic.
The business and productivity facets of psychology are covered in industrial/organizational psychology.
Within a company organization, an industrial/organizational psychologist carries out a variety of tasks including boosting employee productivity, enhancing business operations, and offering management advice.
An industrial/organizational psychologist does not create the company product.
Thus, with the exception of developing business products, all of the following are tasks that an industrial/organizational psychologist may carry out. Option B is the best response.
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People who get population education are also aware of health issues and environment education justify
Answers
99. The centripetal acceleration of a ball of mass m moving at constant speed v in a horizontal circular path of radius r is
(1) zero
(2) constant in direction, but changing in
magnitude
(3) constant in magnitude, but changing in
direction
(4) changing in both magnitude and direction
Answers
The centripetal acceleration of a ball of mass m moving at constant speed v in a horizontal circular path of radius r is constant in direction, but changing in magnitude.
What is magnitude ?A mathematical object's magnitude or size is a characteristic that indicates whether it is bigger or smaller than other objects of the same kind. Formally speaking, the size of an object is the visible outcome of an ordering—of the class of objects to which it belongs.
A magnitude is a measurement of a quantity's size. For instance, an earthquake's Richter scale magnitude, which reflects the size of the earthquake and typically ranges from 1 to 10, is measured. A magnitude 8 earthquake is far more problematic than a magnitude 3 earthquake.
Thus, option 2 is correct.
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the disk of a spiral galaxy supports itself against its own gravity, which would otherwise make it collapse to the galaxy center, by
Answers
The disk of a spiral galaxy supports itself against its own gravity through the centrifugal force generated by the rotation of its stars.
How does the rotation of stars in a spiral galaxy's disk counteract gravitational collapse?The rotation of stars in a spiral galaxy's disk generates a centrifugal force that acts in opposition to the inward force of gravity. This centrifugal force creates a balance, preventing the collapse of the disk toward the galaxy's center.
In a spiral galaxy, such as our Milky Way, the disk consists of billions of stars, gas, and dust arranged in a flattened, rotating structure. The gravitational force between these objects tends to pull them inward. However, the rotation of the disk introduces a counteracting force—the centrifugal force.
As the stars and other matter in the disk orbit around the galactic center, they experience an outward force due to their angular momentum.
The combination of gravity and centrifugal force leads to a stable equilibrium where the inward gravitational force is balanced by the outward centrifugal force.
This equilibrium allows the spiral galaxy's disk to maintain its structure over long periods of time.
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A 5000ton frieight is moving at a speed of 10mph, next to it a 3250lb Ferrari at a speed of 250mph. Both hit the break, but who stops first?
Answers
Answer:
Ferrari would stop first.
Explanation:
The momentum of a moving body is given as:
momentum, P = mass of the body x its velocity
i. For the Freight,
mass = 5000 tons = 4535924 kg
speed = 10 mph = 4.4704 m/s
P = mv
= 4535924 x 4.4704
= 20.28 x \(10^{6}\)
P = 20.28 x \(10^{6}\) kgm/s
ii. For the Ferrari,
mass = 3250 lb = 1474.175 kg
speed = 250 mph = 111.76 m/s
P = mv
= 1474.175 x 111.76
= 16.48 x \(10^{4}\)
P = 16.48 x \(10^{4}\) kgm/s
Comparing the momentum of the two objects, the Ferrari would stop fist when break is applied.
Use the following information about Earth and its moon to determine the distance between them. Earth's mass = 6.0 x 1024 kg Moon's tangential speed = 1,025 m/s Earth's radius = 6.4 x 10 m Moon's mass = 7.3 X 1022 kg 4.6 x 106 m O 3.8 x 108 m O 3.9 x 1011 m
Answers
Answer:
3.8 × 108 m
Explanation:
Use formula: v^2 = G x m central / r
G = 6.77 e-11
Also, it was right on Edge.
Good luck!
The distance between Earth and its moon is 3.8×10⁸ m.
What is centripetal force?
A force that causes a body to follow a curved path is known as a centripetal force. It always moves in a direction that is the opposite of the body's velocity and in the direction of the immediate center of curvature of the path.
It is "a force by which bodies are dragged or driven, or in any manner tend, towards a point as to a center," according to Isaac Newton.
Given parameters:
Mass of the Earth: M = 6.0 × 10²⁴ kg.
Mass of the moon: m = 7.3 × 10²² kg.
Moon's tangential speed: v = 1,025 m/s
Let the distance between the center of Earth and the moon is r.
Hence,
GMm/r² = mv²/r
r = GM/v²
= 6.7 × 10 ⁻¹¹ × 6.0 × 10²⁴ / (1,025)²
= 3.82×10⁸ m.
Hence, by subtracting Earth's radius = 6.4 x 10⁶ m, we get, the distance between Earth and its moon is 3.8×10⁸ m.
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In relation to line locators conductive is
A) a direct connection with the pipe and transmitter
B) an indirect connection with radio waves
Answers
In relation to line locators, conductive refers to a direct connection between the pipe and transmitter. Conductive locating involves connecting a transmitter to a metallic pipe or cable and then using a receiver to detect the signal transmitted through the pipe or cable.
The transmitter sends an electrical signal through the conductive material, which is then picked up by the receiver. This technique is particularly useful when locating pipes or cables that are buried underground or hidden behind walls. By using conductive locating, line locators can accurately determine the location, depth, and direction of the pipe or cable. In contrast, an indirect connection with radio waves, as in option B, is referred to as inductive locating, which involves detecting the electromagnetic field around the pipe or cable. While inductive locating can be useful in some situations, such as locating non-conductive pipes or cables, it is less accurate than conductive locating. Overall, conductive locating is a key technique used by line locators to accurately and efficiently locate buried or hidden pipes and cables.
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What observational evidence supports the conclusion that most of the mass of the milky way is in the form of dark matter?.
Answers
Surprisingly fast orbital speeds of stars and gas clouds located far from the galactic center indicate that these objects are subject to gravitational influences.
What is gravitational effects?The moon is maintained in its orbit around Earth by gravity, as are the planets in their orbits around the sun. Ocean tides are a result of the moon's gravitational effect on the oceans. The stuff that stars and planets are comprised of is pulled together by gravity to form them.
involving or pertaining to the attraction between two masses: Ocean tides rise and fall due to the moon's gravitational pull. of or pertaining to a strong inclination or movement in the direction of something or someone: There has been a lot of research on why they gravitate toward destructive behavior.
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Levi decides to examine the effect of fertilizer on the growth of tomato plants. He chooses four plants for his experiment and applies varying amounts of fertilizer to the three of them. He does not apply fertilizer to one plant.
Over a 15-day period, the plants receive fertilizer on Days 1, 4, 7, 10, and 13. Levi measures the height of all of his plants with a meter stick on Days 3, 6, 9, 12, and 15. He also makes sure to hold all experimental factors constant except for the fertilizer.
Which statement describes what Levi did to prepare the control group in his experiment?
Levi applied different amounts of fertilizer to three of his plants.
Levi did not apply any fertilizer to one of his plants..
Levi held all experimental factors constant except for fertilizer., ,
Levi measured his plants on five separate days.
Answers
Answer:
Levi did not apply any fertilizer to one of his plants..
Explanation:
In an experiment, there are two major groups namely: control group and experimental group. Control group is the group in an experiment that does not receive the experimental treatment i.e. the group which the independent variable is not applied to.
In this case, Levi is trying to examine the effect of fertilizer on the growth of tomato plants where he used varying amounts of fertilizer on three of the four plants he used for the experiment. The fourth plant did not receive any amount of fertilizer, which is the independent variable (variable being manipulated or changed). This means that Levi prepared the control group in his experiment by NOT APPLYING ANY FERTILIZER TO ONE OF HIS PLANTS.
explain the effect of impurities on melting and boiling point
Answers
i only know the example :- adding salt to water will lead to increase in its boiling point .
Which of the following situations will not generate stress?
a.
Driving in traffic
b.
Sleeping
c.
Opening a birthday present
d.
Watching a soap opera
Answers
Answer:
Sleeping
Explanation:
Driving in traffic is stressful because you may be late for wherever you are going,
Opening a birthday present is stressful because you don't know what is inside until you open it.
Watching a soap opera is stressful because you do not know what will happen next,
Sleeping is not stressful as long as you don't bring stressful topics to bed.
What would changing the frequency of a wave do to the wave?
Answers
The noble gas neon is used for filling neon signs. Like other noble elements, it has a full octet (complete outer energy level) of electrons, which makes the gas A. freeze at room temperature. B. react with other gases in the air. C. unlikely to combine with other elements. D. solidify at standard pressure and temperature, chiny pray-colored solid at room
Answers
Answer:
C. unlikely to combine with other elements.
Explanation:
In Chemistry, electrons can be defined as subatomic particles that are negatively charged and as such has a magnitude of -1.
Valence electrons can be defined as the number of electrons present in the outermost shell of an atom. Valence electrons are used to determine whether an atom or group of elements found in a periodic table can bond with others. Thus, this property is typically used to determine the chemical properties of elements.
Noble gases are chemical elements with eight valence electrons and as such have a full octet. Some examples are argon, neon, etc.
Hence, the full octet makes the gas (neon) unlikely to combine with other elements.
answerplease …..(i had to cut off answet C but it is they have a shiny appearance
Answers
Metals have shiny apperances
Which observational techniques is most appropriate for measuring doppler shifts?
Answers
The observational technique most appropriate for measuring Doppler shifts is spectroscopy, specifically using the Doppler effect in the analysis of spectral lines.
The Doppler effect is the change in frequency or wavelength of a wave (in this case, light) observed when there is relative motion between the source of the wave and the observer. In the context of astronomy, the Doppler effect is commonly used to measure the radial velocity of celestial objects, such as stars, galaxies, and even planets.
There are two main spectroscopic techniques used to measure Doppler shifts:
1. Radial Velocity Method: This technique is used to measure the line-of-sight velocity of an object. It relies on observing the Doppler shift of spectral lines as the object moves toward or away from the observer.
2. Redshift/Blueshift Analysis: This technique is commonly used in cosmology to study the expansion of the universe. It involves measuring the redshift or blueshift of spectral lines from distant objects, such as galaxies.
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which of these is not a point source pollution
1. nitrates found in a river
2. someone dumping used oil in their backyard
3. factory smokestack
4. leaking oil tanker
Answers
What does our atmosphere protect us from?
Answers
The atmosphere protects life on Earth by filtering harmful UV radiation, regulating solar radiation and heat, shielding against cosmic rays and space debris, maintaining atmospheric pressure for respiration, and mitigating the impact of meteorological hazards.
Our atmosphere provides several key protections to life on Earth:
Ultraviolet (UV) Radiation: The atmosphere contains the ozone layer, which helps filter out a significant amount of harmful UV radiation from the Sun. UV radiation can cause skin damage, including sunburns and an increased risk of skin cancer.
Solar Radiation and Heat: The atmosphere absorbs and scatters a portion of the Sun's solar radiation, reducing the intensity of direct sunlight that reaches the Earth's surface. It helps regulate temperatures by trapping heat through the greenhouse effect, preventing extreme temperature fluctuations.
Cosmic Rays and Space Debris: The atmosphere acts as a shield against high-energy cosmic rays and most space debris, such as small meteoroids, by causing them to burn up or disintegrate upon entry. This protection prevents them from reaching the Earth's surface and causing potential harm.
Atmospheric Pressure: The atmosphere exerts pressure on the Earth's surface, creating a stable environment for life. It allows us to breathe comfortably by ensuring that air molecules are present at a sufficient density for respiration.
Protection from Meteorological Hazards: The atmosphere plays a crucial role in weather patterns, helping to distribute heat, moisture, and energy across the planet. It provides a buffer against extreme weather events like hurricanes, tornadoes, and severe storms, helping to mitigate their impact.
Therefore, our atmosphere serves as a protective barrier that shields us from various harmful external factors, maintaining a stable and habitable environment for life on Earth.
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