5. Suppose a cup of cocoa cooled from 90° C to 60° C after 10 minutes in a room whose temperature was 20° C . Use Newton’s law of cooling [T − Ts = (T0 − Ts )⋅ e−k⋅t ] to answer the following questions: a) How much longer would it take the cocoa to cool to 35° C ? b) Instead of being left to stand in a room, the cup with initial temperature 90° C is placed in a freezer whose temperature is −15° C . How long will it take the cocoa to cool from 90° C to 35° C ?

Answers

Answer 1

Answer:

a) t = 1051.6 sec = 17.5 min

b) t = 795.5 sec = 13.25 min

Explanation:

First of all we use the initial data to find out constant 'K'.

T - Ts = (T₀ - Ts) e^(-kt)

Here, we have:

T = Final Temperature = 60° C

Ts = Surrounding Temperature = 20° C

T₀ = Initial Temperature = 90° C

t = time = 10 min = 600 sec

k = constant = ?

Therefore,

60° C - 20° C = (90° C - 20° C).e^(-k600)

40° C/70° C = e^(-k600)

ln (0.57142) = -600k

k = 9.327 x 10⁻⁴ sec⁻¹

a)

Now, for this case we have:

T = Final Temperature = 35° C

Ts = Surrounding Temperature = 20° C

T₀ = Initial Temperature = 60° C

t = time = ?

k = constant = 9.327 x 10⁻⁴ sec⁻¹

Therefore,

35° C - 20° C = (60° C - 20° C).e^(-9.327 x 10⁻⁴ sec⁻¹ x t)

15° C/40° C = e^(-9.327 x 10⁻⁴ sec⁻¹ x t)

ln (15/40) = - 9.327 x 10⁻⁴ sec⁻¹ x t

t = 1051.6 sec = 17.5 min

b)

Now, for this case we have:

T = Final Temperature = 35° C

Ts = Surrounding Temperature = -15° C

T₀ = Initial Temperature = 90° C

t = time = ?

k = constant = 9.327 x 10⁻⁴ sec⁻¹

Therefore,

35° C + 15° C = (90° C + 15° C).e^(-9.327 x 10⁻⁴ sec⁻¹ x t)

50° C/105° C = e^(-9.327 x 10⁻⁴ sec⁻¹ x t)

ln (50/105) = - 9.327 x 10⁻⁴ sec⁻¹ x t

t = 795.5 sec = 13.25 min


Related Questions

Two 1.50-V batteries—with their positive terminals in the same direction—are inserted in series into the barrel of a flashlight. One battery has an internal resistance of 0.390 Ω, the other an internal resistance of 0.120 Ω. When the switch is closed, a current of 600 mA occurs in the lamp.What fraction of the power dissipated is dissipated in the batteries?

Answers

Answer:

im sorry i dont wanna give you a wrong answer if you want one tho ill give it to you

Explanation:

You put mass m1 of ice cooled to -20C into mass m2 of water at 2C. Both are in a thermally insulated chamber. In the final state of the system: A. Everything turns to ice at a temperature below 0C. B. Everything melts and is at a temperature above 0C. C. There is a mixture of water and ice as the final state. D. The water and ice never reach the same temperature. E. There is not enough information to find the final temperature.

Answers

Answer:

E. There is not enough information to find the final temperature.

Explanation:

We do not the actual masses of ice and water involved in the question, so we cannot determine if the water freezes or the ice melts. So, there is not enough information to find the final temperature.

A holiday ornament in the shape of a hollow sphere with mass 0.015 kg and radius 0.055 m is hung from a tree limb by a small loop of wire attached to the surface of the sphere. If the ornament is displaced a small distance and released, it swings back and forth as a physical pendulum.
Calculate its period. (You can ignore friction at the pivot. The moment of inertia of the sphere about the pivot at the tree limb is 5MR²/3.)
Take the free-fall acceleration to be 9.80 m/s². Express your answer using two significant figures.

Answers

Answer: 0.61 s

Explanation:

Given

Mass of object, m = 0.015 kg

Radius of object, r = 0.055 m

Acceleration of object, g = 9.8 m/s²

In a pendulum,

T = 2π * √[I /(mgd)]

The moment of Inertia, I of a hollow sphere is given by

I(sphere) = 2/3MR² + MR²

I(sphere) = 5/3MR²

Also, d = R

Substituting these into the first equation, we have

T = 2π * √[(5/3MR²) / (mgr)]

T = 2π * √[(5/3r) / (g)]

T = 2 * 3.142 * √(5/3 * 0.055) / (9.8)]

T = 6.284 * √(0.092/9.8)

T = 6.284 * √0.00939

T = 6.284 * 0.097

T = 0.6095 s

To 2 significant figures,

The period is 0.61 s

If a 2V battery is connected to the wire in one direction, the electrode that was the cathode becomes the anode and vice verse, but when the battery is connected the other way the cathode and anode do not switch. Explain why this is so, and what the voltages of the two situations are.

Answers

Answer:

1. This is so because of the charging and discharging phenomenon of the battery.

2. Voltage when fully charged: approximately 2.15 volts

Voltage when in use: drops below 2.15v

Explanation:

The anode is the electrode where electricity flows into. In contrast, the cathode is the electrode where the electricity flows out of.  When a battery is connected to a load the electricity flows from the positive terminal to the negative terminal. In this case, the positive terminal is the cathode, and the negative terminal is the anode.  Here the cathode and anode do not switch,

But when the battery is being charged, the electricity flows into the positive terminal instead of out of it. In this case, the roles are reversed, the electrode that was the cathode becomes the anode, and the anode becomes that cathode.

A fully charged 2volt battery has a voltage of approximately 2.15 volts. A fully discharged 2 volt battery has a voltage of 1.9 volts

A square current loop 5.20 cm on each side carries a 460 mA current. The loop is in a 0.900 T uniform magnetic field. The axis of the loop, perpendicular to the plane of the loop, is 30° away from the field direction.
What is the magnitude of the torque on the current loop?

Answers

The magnitude of the torque on the current loop is 0.0055 Nm

Explanation:

Given data,

We  have the formula,

T= u x B

Where u=  i x A

T= i×A×B ×sin(30)

T=0.46×0.52² ×0.900×0.5

T=0.0055 Nm

The magnitude of the torque on the current loop is 0.0055 Nm

**URGENT, I WILL PAY 30 POINTS, PLEASE HELP**
Which wave has the shortest wavelength, assuming the axis for each wave is identical?

Answers

All three windows are the same size.

A has 10 complete waves visible through the window. B has 3, and C has 4.

So A must have the smallest wavelengths.

The answer is A.

The wavelength is the length to each curve. Each answer choice has the same length of a box so we can count the amount of curves in each option.

Option A has 10 visible curves.

Option B has 3 visible curves.

Option C has 4 visible curves.

Since option A has the most curves, that means that it has the shortest wavelengths.

Best of Luck!

With the two spheres separated by 1 cm you measure the magnitude of the force between the spheres to be LaTeX: F_{12}F 12 . Now you remove the second sphere, and then bring a third identical sphere that is initially uncharged into brief contact with the first sphere before separating them by 1 cm. What is the approximate magnitude of the force between the first and third spheres?

Answers

Answer:[tex]0.25f_{12}[/tex]

Explanation:

Given

When Sphere 1 and 2 are present then force is [tex]f_{12}[/tex]

suppose q is the charge on both the sphere and [tex]d=1\ cm[/tex] is the distance between them then

[tex]f_{12}=\dfrac{kq^2}{d^2}[/tex]

Now sphere 2 is removed and sphere 1 is brought in contact with sphere 3

Charge will be automatically  distributed among two spheres

i.e. both will acquire a charge of [tex]0.5 q[/tex]

Now force between them is

[tex]f'=\dfrac{k\times 0.5q\times 0.5q}{d^2}[/tex]

[tex]f'=0.25\times \dfrac{kq^2}{d^2}[/tex]

[tex]f'=\dfrac{f_{12}}{4}[/tex]

The International Space Station is orbiting at an altitude of about 370 km above the earth's surface. The mass of the earth is 5.976 × 1024 kg and the radius of the earth is 6.378 × 106 m. Assuming a circular orbit, what is the period of the International Space Station's orbit?

Answers

Answer:

T = 5516.63 seconds

Explanation:

Given that,

The International Space Station is orbiting at an altitude of about 370 km above the earth's surface.

Mass of the Earth, [tex]M=5.976 \times 10^{24}\ kg[/tex]

Radius of Earth, [tex]r=6.378\times 10^6\ m[/tex]

We need to find the period of the International Space Station's orbit. It is a case of Kepler's third law. Its mathematical form is given by :

[tex]T^2=\dfrac{4\pi^2}{GM}\times R^3[/tex]

R = r + h

[tex]T^2=\dfrac{4\pi^2}{6.67\times 10^{-11}\times 5.976 \times 10^{24}}\times (370000+6.378\times 10^6)^3\\\\T^2=30433264.1641\ s\\\\T=5516.63\ s[/tex]

So, the period of the International Space Station's orbit is 5516.63 seconds.

A uniform 1.6-kg rod that is 0.89 m long is suspended at rest from the ceiling by two springs, one at each end. Both springs hang straight down from the ceiling. The springs have identical lengths when they are unstretched. Their spring constants are 31 N/m and 63 N/m. Find the angle that the rod makes with the horizontal.

Answers

Answer:

8.27°

Explanation:

To angle difference will be determined by the difference in the displacement of the springs, produced by the weight of the center of mass of the rod.

[tex]d=y_1-y_2=\frac{F_1}{k_1}-\frac{F_2}{k_2}=\frac{0.5mg}{31N/m}-\frac{0.5mg}{63N/m}\\\\d=0.5(1.6kg)(9.8m/s^2)[\frac{1}{31N/m}-\frac{1}{63N/m}]=0.128m[/tex]

by a simple trigonometric relation you obtain that the angle:

[tex]sin\theta=\frac{d}{l}=\frac{0.128m}{0.89m}=0.144\\\\\theta=sin^{-1}(0.144)=8.27\°[/tex]

hence, the angle between the rod and the horizontal is 8.27°

summarize the physical reasons that sound waves travel at different speeds through different mediums ​

Answers

Final answer:

The speed of sound varies in different media due to the rigidity (or compressibility in gases) and density of the medium. More rigid and less compressible media enable faster sound travel, while greater density can slow it down. Temperature also plays a role, with higher temperatures often leading to faster sound propagation.

Explanation:Understanding the Speed of Sound in Different Mediums

Sound waves travel at different speeds through different media because of the medium's rigidity and density. A medium's rigidity, or in the case of gases, compressibility, greatly influences the speed of sound. The more rigid or less compressible a medium is, the faster sound travels through it. Additionally, sound travels through a medium of lower density faster when the materials have similar rigidity, because the energy transfer between particles is more efficient.

Liquids and solids, for instance, are harder to compress and more rigid compared to gases, which accounts for the higher speed of sound in these media. However, the relationship is not straightforward with density, as an increased density can actually slow the propagation of sound, due to the increased mass particles have to move. Finally, temperature also affects the speed at which sound travels; hotter media makes particles more energetic and thus can increase the speed of sound.

It's important to understand these physical principles when considering applications such as medical imaging using ultrasonic waves or studying the properties of materials through acoustic analysis.

What do the single electrons in nitrogen do for a triple bond?​

Answers

Nitrogen could form 3 bonds based on octet rule, because it has 5 valence electrons. That means it needs 3 bonds.

Explanation:

A nitrogen atom can fill its octet by sharing three electrons with another nitrogen atom, forming three covalent bonds, a so-called triple bond. A triple bond isn't quite three times as strong as a single bond, but it's a very strong bond.Every covalent bond is a sharing of two electrons between two atoms. A double bond is 4 electrons being shared (2x2). Therefore a triple bond is 6 electrons being shared (2x3)Triple bonds are stronger than double bonds due to the the presence of two pi bonds rather than one. Each carbon has two sp hybrid orbitals, and one of them overlaps with its corresponding one from the other carbon atom to form an sp-sp sigma bond.A single lone pair can be found with atoms in the nitrogen such as nitrogen in ammonia , two lone pairs can be found with atoms in the chalogen group such as oxygen in water and the halogen can carry three lone pairs such as in hydrogen chloride. Nitrogen has 2 lone pairs.

What type of energy is the sum of an object’s potential and kinetic energy?

Answers

Answer: its mechanical energy

Explanation:

Answer:

Mechanical energy edg2021

Explanation:

The sum of an objects potential and kinetic energy is mechanical energy.

David wants to experiment with the device, so he connects an ammeter into the circuit and measures 11.5 AA when the device is connected to the car's battery. From this, he calculates the time to boil a cup of water using the device. If the energy required is 100 kJkJ , how long does it take to boil a cup of water?

Answers

Answer:

2.42hours

Explanation:

To calculate the time taken to boil the cup of water, we will use the formula

Q = It where

Q is the total energy required to boil the water = 100KJ = 100,000Joules

I is the current = 11.5A

t is the time taken to boil the water

t = Q/I

t = 100,000/11.5

t = 8695.65seconds

t = 2.42hours

To calculate the time to boil water using a car battery, multiply the current by the typical car battery voltage to find the power and then use the energy required divided by the power to find the time. In this case, it takes approximately 12 minutes and 4 seconds to boil the water.

To determine how long it takes to boil a cup of water using an electrical device, we need to calculate the time based on the power and energy required. The energy required to boil the water is given as 100 kJ. David measured a current of 11.5 A with an ammeter when the device is connected to the car's battery. To find the time, we need the voltage of the car's battery, which is typically 12 V for most cars. The power (P) can be calculated using the formula P = I  imes V where I is the current and V is the voltage. Therefore, the power is P = 11.5 A  imes 12 V = 138 W (watts). Next, we convert the energy required to watt-seconds by multiplying 100 kJ by 1,000 to get 100,000 J. Then, we calculate the time (t) using the formula t = Energy / Power. So, t = 100,000 J / 138 W \<- approximately 724.64 s, or roughly 12 minutes and 4 seconds.

A ray of light, traveling through air, is incident on a smooth transparent liquid surface at an angle of 13 degrees with respect to the normal of the surface. What is the refraction angle of the light in the liquid if the index of refraction of the liquid is 1.54? Return the angle in degrees and rounded to 2 decimal places.

Answers

Answer:

The refraction angle of the light in the liquid is 8.40 degrees.

Explanation:

Given:

A ray of light passing through air to liquid.

Air is medium 1 and liquid is medium 2.

Angle of incidence [tex](\theta_1)[/tex] = 13°

Refractive index, [tex](n_2)[/tex] = 1.54

We have to find the angle of refraction:

Let the angle of refraction be "[tex]\theta_2[/tex]" .

Formula to be used:

[tex]n_1\times sin(\theta_1) =n_2\times sin(\theta_2)[/tex]

Note:

Index of refraction of air  [tex](n_1)[/tex] = 1

Accordingly:

Using Snell's law and plugging the values.

⇒ [tex]n_1\times sin(\theta_1) =n_2\times sin(\theta_2)[/tex]

⇒ [tex]1\times sin(13) =1.54\times sin(\theta_2)[/tex]

⇒ [tex]\frac{1\times sin(13)}{1.54} = sin(\theta_2)[/tex]

⇒ [tex]\frac{1\times 0.2249}{1.54} = sin(\theta_2)[/tex]     ...sin(13) =0.2249

⇒ [tex]\theta_2=sin^-^1(\frac{0.2249}{1.54})[/tex]

⇒ [tex]\theta_2=sin^-^1(0.145)[/tex]

⇒ [tex]\theta_2=8.3974[/tex] degrees.

⇒ [tex]\theta_2 = 8.40[/tex] degrees ...Rounded to 2 decimal place.

The refraction angle of the light in the liquid is 8.40 degrees.

Molecular clouds range in mass from a few times the mass of our Sun (solar masses) to 10 million solar masses. Individual stars range from 0.08 to about 150 solar masses. What does all of this imply about how stars form from molecular clouds

Answers

Answer:

Explained in Depth.

Explanation:

It is all matter of what kind of stars are we talking about, for simplicity let's say we are talking about normal stars such as our sun.

If there is a molecular cloud that has a mass that is slightly larger than our sun then it is possible that the gravity will eventually pull together cloud into a sphere that would have enough mass to start nuclear fusion which is important to become a star.

Mass of such cloud would be 1.98x10^30Kg almost equal to the sun's mass.

All of this implies that stars are formed when there is enough mass to let gravity pull it all together into a sphere that has enough gravitational pull to start nuclear fusion inside the core.

Molecular clouds, with masses ranging from a few times the mass of the Sun to 10 million solar masses, form stars when their dense cores collapse due to gravity overcoming internal pressure. This process involves clumps and cores within the clouds, eventually leading to the birth of a star as gravity causes the core to contract and increase in density significantly.

Molecular clouds range in mass from a few times the mass of our Sun (solar masses) to 10 million solar masses, while individual stars vary from 0.08 to about 150 solar masses. This significant range in mass implies a crucial relationship in star formation.

Molecular clouds, also known as stellar nurseries, contain complex structures including clumps and cores. Clumps within these clouds have masses between 50 and 500 solar masses, and are subdivided into even denser regions called cores, which can serve as the embryos of stars due to their high density and low temperature. As gravity pulls the material in these cores inward, the material collapses under its own weight, eventually forming a star.

The ongoing battle between gravity and pressure defines the star formation process. When gas atoms in the cores are dense and cold enough, gravity overcomes internal pressure, leading to collapse and the birth of a star. This collapse reduces the radius and increases the density of the core by a factor of nearly [tex]10^{20}[/tex], resulting in the formation of a dense, hot ball of matter where nuclear reactions can begin, giving rise to a new star.

The data indicate the populations of mammals in the Florida Everglades in different years over the past two decades. The Burmese python, a non-native species, was introduced to Florida as an exotic pet. After Hurricane Andrew hit Florida in 1992, many pet owners lost track of their non-native snakes. The biodiversity of the Everglades has decreased since then. According to the data, what hypothesis is best supported with regard to Burmese pythons and Florida Everglade biodiversity? A) Burmese pythons are omnivorous and have decreased all populations of mammals. B) Burmese pythons compete with the white-tailed deer most directly for food sources. C) Burmese pythons lack natural predators and can utilize a wide variety of food sources in the Everglades. D) Burmese pythons carry diseases and parasites that directly impact the mammal populations of the Everglades.

Answers

Answer:

C) Burmese pythons lack natural predators and can utilize a wide variety of food sources in the Everglades.

Explanation:

Due to it being an invasive specie (naturally found in South Asia), and also one of the five largest species of snakes in the world, the Burmese pythons lack natural predators in this new territories.

The Burmese viper is also an opportunistic hunter and would eat anything it can overpower, it easily made a wide range of food varieties in these swamps.

The best-supported hypothesis regarding the impact of Burmese pythons on the biodiversity of the Florida Everglades is option C: Burmese pythons lack natural predators and can utilize a wide variety of food sources in the Everglades.

Burmese pythons have become a notorious invasive species in Florida Everglades, with their introduction traced back to events such as Hurricane Andrew. This species has a significant negative impact on local ecosystems primarily due to its wide-ranging diet and absence of natural predators, which allows for unchecked population growth. The data indicating a decrease in Everglades' mammal populations correlates with the introduction and proliferation of pythons, who can consume a broad array of species. Similar scenarios observed in other ecosystems, like the brown tree snake in Guam and the Nile perch in Lake Victoria, support the idea that invasive predators can cause extinctions and greatly disrupt native biodiversity. The Burmese python's adapting capabilities and generalist diet make it a formidable invader that furthers the decline of various mammal populations, sustains its population expansion, and consequently diminishes Everglades biodiversity.

When water is boiled at a pressure of 2.00 atm, the heat of vaporization is 2.20×106J/kg2.20×10
6
J/kg and the boiling point is 120∘C120

C. At this pressure, 1.00 kg of water has a volume of 1.00×10−3m31.00×10
−3
m
3
, and 1.00 kg of steam has a volume of 0.824m30.824m
3
. (a) Compute the work done when 1.00 kg of steam is formed at this temperature. (b) Compute the increase in internal energy of the water.

Answers

Answer:

Explanation:

a ) When 1 kg water is boiled at constant pressure of 1  atm , its volume increases by following volume

(.824 - .001 )m³

.823 m³

work done by steam  = increase in volume x pressure

.823 x 10⁵ J

Heat added

=  latent heat of vaporization x mass

= 2260000 J x 1

= 22.6 x 10⁵ J

Increase in internal energy of gas

= heat added - work done by gas

= (22.6 - .823) x 10⁵ J

= 21.777 x 10⁵ J .

Explain how wind and water can contribute to
weathering, and are also agents of erosion and
deposition.​

Answers

agents of erosion and deposition- water wind vegation and human action (also gravity)
wind and water can break down the proccess of weathering

Final answer:

Wind causes erosion by deflating fine-grained particles, leading to landforms like desert pavements. It deposits sediments forming dunes. To prevent wind erosion, planting vegetation, creating windbreaks, and careful land management are effective.

Explanation:

How Wind Causes Erosion

Erosion is the process by which natural forces move sediments and other soil components from one place to another. Wind causes erosion primarily through a process known as deflation, which is the removal of loose, fine-grained particles by the turbulent action of the wind. Over time, these actions can result in landforms such as desert pavements, where only larger rocks remain because the smaller particles have been blown away.

Sediments Deposited by Wind

Sediments like sand and dust can be carried over great distances by wind before being deposited. These sediments can form various wind-deposited landforms, such as dunes. Dunes are hills of loose sand built by aeolian processes and are one of the most recognizable landforms deposited by wind.

Preventing Wind Erosion

To prevent wind erosion, practices such as planting vegetation cover, creating windbreaks, and managing land use to avoid overexposure of the soil are effective. Vegetative cover helps to bind the soil together and windbreaks, such as trees and shrubs, reduce the wind speed at ground level, preventing the soil from being picked up.

You place a 10 kg block on a ramp with an angle of 20 degrees. You push the block up the ramp giving it an initial velocity of 15 m/s. If the coefficient of friction between the block and the ramp is 0.4, find the total distance the block travels before it turns around and slides back down the ramp.

Answers

Answer:

L = 15.97 m

Explanation:

Given:-

- The mass of the block, m = 10 kg

- The inclination of ramp, θ = 20°

- The initial speed, Vi = 15 m/s

- The coefficient of friction u = 0.4

Find:-

find the total distance the block travels before it turns around and slides back down the ramp.

Solution:-

- The total distance travelled by the block up the ramp is defined when all the kinetic energy is converted into potential energy and work is done against the friction. Final velocity V2 = 0.

- Develop a free body diagram of the block. Resolve the weight "W" of the block normal to the surface of ramp. Then apply equilibrium condition for the block in the direction normal to the surface:

                                N - W*cos( θ ) = 0

Where, N : The contact force between block and ramp.

                                N = m*g*cos ( θ )

- The friction force (Ff) is defined as:

                               Ff = u*N

                               Ff = u*m*g*cos ( θ )

- Apply the work-energy principle for the block which travels a distance of "L" up the ramp:

                               K.E i = P.E f + Work done against friction

Where,  K.E i = 0.5*m*Vi^2

             P.E f = m*g*L*sin( θ )

             Work done = Ff*L

- Evaluate "L":

                        0.5*m*Vi^2 = m*g*L*sin( θ ) + u*m*g*cos ( θ )*L

                        0.5*Vi^2 = g*L*sin( θ ) + u*g*cos ( θ )*L

                        0.5*Vi^2 = L [ g*sin( θ ) + u*g*cos ( θ ) ]

                        L = 0.5*Vi^2 / [ g*sin( θ ) + u*g*cos ( θ ) ]

                        L = 0.5*15^2 / [ 9.81*sin( 20 ) + 0.4*9.81*cos ( 20 ) ]

                        L = 15.97 m

With current technologies and solar collectors on the ground, the best we can hope for is that solar cells will generate an average (day and night) power of about 230 watts/m2watts/m2 . What total area would we need to cover with solar cells to supply all the power needed for the United States

Answers

Answer:

The question is missing

The total annual U.S. energy consumption is about 2 × 10^20 J

Explanation:

So, if the annual Energy is

2 × 10^20J

Let find the power usage of this energy

We know that

Power = Energy / Time

Now, the time is one year, so we have to convert one year to seconds

1year = 365days

365days = 365 × 24hours

365 × 24 hours = 365 × 24 × 3600 seconds

Then,

1year = 31,536,000seconds

Then,

P = E / T

P = 2 × 10^20 / 31,536,000

P = 6.342 × 10^12 Watts

The power intensity is given as

I = P/A

Then,

A = P / I

Where,

P is power, I is intensity and A is area

Given that, I = 230 W/m²

A = 6.342 × 10^12 / 230

A = 2.757 × 10^10 m²

To meet the United States' energy needs using solar cells generating 230 watts/m², an area of approximately 14,500 km² is required.

To determine the total area of solar cells needed to supply all the power needed for the United States, we start with the given average power generation of 230 watts/m².

The energy needs for the United States per year is given as 1.05 × 10²⁰ Joules.

Convert Energy to Power:

First, we need to convert this annual energy requirement into average power, knowing that there are 31,536,000 seconds in a year (365 days × 24 hours/day × 3600 seconds/hour).

Average Power Required = [tex]\frac{Total Energy}{Time}[/tex] = (1.05 × 10²⁰J) ÷ {31,536,000 s} ≈ 3.33 × 10¹² watts

Calculate the Area Required:

If each square meter generates an average power of 230 watts, we can find the total area (A) by dividing the total power required by the power generated per square meter.

Required Area = [tex]\frac{Total Power Required}{Power Generated per unit area}[/tex] = 3.33 × 10¹² watts ÷ 230 watts/m² ≈ 1.45 × 10¹⁰ m²

To find the area in square kilometers, we convert square meters to square kilometers knowing that 1 km² = 1,000,000 m².

Total Area in km² = (1.45 × 10¹⁰ m²) ÷ (1,000,000 m²/km²) = 14,500 km²

Thus, approximately 14,500 km² of solar cells would be needed to generate enough power to meet the United States' energy needs.

Flasher units are being discussed. Technician A says that only a DOT-approved flasher unit should be used for turn signals. Technician B says that a parallel (variable-load) flasher will function for turn signal usage, although it will not warn the driver if a bulb burns out. Who is right?
a. Technician A onlyb. Technician B onlyc. Both Technicians A and Bd. Neither Technician A nor B

Answers

Answer: C

Both Technicians A and B

Explanation:

Only a DOT-approved flasher unit should be used for turn signals. And a parallel (variable-load) flasher will function for turn signal usage, although it will not warn the driver if a bulb burns out.

Water occupies two main fluid compartments within the body, the intracellular fluid compartment and the extracellular fluid compartment. Which of the following statements is true concerning the volume of intracellular fluidA. The ICF fluid compartment changes, so there is no way to determine the amount of water at a given timeB. Approx. One third of the water is in the ICF compartmentC. Approx. Two thirds of the water is in the ICF compartmentD. All of the water is in the ICF compartment

Answers

Answer:

C. Approx. Two thirds of the water is in the ICF compartment

Explanation:

The body cells are bathed in fluids internally and externally. The water inside the cells make up about 42% of the total body weight and is called the intracellular fluid (ICF). The rest of the fluid outside the cells is called extracellular fluid (ECF) and is separated from the intracellular fluid by a semipermeable membrane that surrounds the cell, and only allows fluid to flow in and out of the cells, but prevents unwanted molecules or materials from getting in.

A battery connected across two parallel metal plates. There is a uniform E-field between the plates, and a positive charge experiences a drop in potential upon traveling from the left plate to the right plate. If the separation of the plates is 0.002 m, determine the magnitude of the electric field in the air gap

Answers

Answer:

The magnitude of the electric field in the air gap [tex]E = 0.00036 C[/tex]

Explanation:

The Electric field E between the plates, [tex]E = \frac{q}{4\pi \epsilon_{0} r^{2} }[/tex]

Where q = the positive charge

r = separation of the plates= 0.002 m

[tex]\frac{1}{4\pi \epsilon_{0} } = 9 * 10^{9} Nm^{2} /C^{2}[/tex]

[tex]E = \frac{9 * 10^{9} q}{0.002^{2} } \\E = \frac{9 * 10^{9} q}{4 * 10^{-6} } \\E = 2.25* 10^{15} q[/tex]

The elementary positive charge, q = 1.602176634×10−19 C

[tex]E = 2.25 * 10^{15} * 1.602176634×10^{-19} \\E = 0.00036 C[/tex]

There is a Limited amount of energy available on earth. Why is it important that people conserve energy?

Answers

Answer:

If humans conserve energy then we will have energy for alonger amount of time.

Explanation:

Diffuse reflection occurs when the size of surface irregularities is

Answers

Diffuse reflection occurs when the irregularities of a surface are comparable to or larger than the wavelength of the incident light, causing light to scatter in multiple directions.

Diffuse reflection occurs when light reflects off a surface that has irregularities comparable to or larger than the wavelength of the incident light. The surface's unevenness causes the incoming light rays to reflect in multiple directions, giving a non-glossy or matte appearance to the surface. This should be contrasted with specular reflection, where a smooth surface reflects light in a singular, coherent direction, maintaining the angle of incidence equal to the angle of reflection.

A familiar example of diffuse reflection is the way sunlight illuminates a room; the light is scattered by the walls and objects, which have microscopically rough surfaces. In contrast, a mirror provides a clear image due to specular reflection because its surface irregularities are much smaller than the wavelength of visible light. This principle of diffuse versus specular reflection is fundamental in understanding how different materials and surfaces affect the quality of reflected light.

A Young's interference experiment is performed with blue-green laser light. The separation between the slits is 0.500 mm, and the screen is located 3.14 m from the slits. The first bright fringe is located 3.24 mm from the center of the interference pattern. What is the wavelength of the laser light?

Answers

Answer:

Wavelength of laser light will be [tex]5.15\times 10^{-7}m[/tex]

Explanation:

We have given distance between the slits d = 0.5 mm = [tex]0.5\times 10^{-3}m[/tex]

Distance between screen and slits D = 3.14 m

Distance of bright fringe from center [tex]y=3.24mm=3.24\times 10^{-3}m[/tex]

It is known that [tex]sin\Theta =\frac{y}{D}=\frac{3.24\times 10^{-3}}{3.14}=1.031\times 10^{-3}m[/tex]

It is also know that [tex]m\lambda =dsin\Theta[/tex], here m = 1 for first bight fringe.

[tex]1\times \lambda =0.5\times 10^{-3}\times 1.031\times 10^{-3}[/tex]

[tex]\lambda =5.15\times 10^{-7}m[/tex]

So wavelength of laser light will be [tex]5.15\times 10^{-7}m[/tex]

A cat walks along a plank with mass M= 7.00 kg. The plank is supported by two sawhorses. The center of mass of the plank is a distance d1= 0.850 m to the left of sawhorse B. When the cat is a distance d2= 1.11 m to the right of sawhorse B, the plank just begins to tip.If the cat has a mass of 3.6 kg, how far to the right of sawhorse B can it walk before the plank begins to tip?

Answers

Final answer:

In the Physics topic of static equilibrium, this problem finds the distance the cat can walk right from sawhorse B before the plank tips. The calculated distance, 0.56m, is found by setting the torques exerted by the cat and plank equal to each other and solving for the unknown distance.

Explanation:

The category of this problem belongs to Physics, specifically in the topic of static equilibrium. In this problem, we want to find out how far right the cat can walk from sawhorse B before the plank begins to tip.

First, realize the plank will begin to tip once the center of mass of the system (plank plus cat) is directly above sawhorse B.

To maintain equilibrium, the torque exerted by the cat must be equal to the torque exerted by the plank, given by Torque = Force x Distance (or) m1d1 = m2d2. The force is the weight of the object.

So we have, M*d1 = (M+m)*d2, here M is the mass of the plank, m is the mass of the cat. By substituting the known values (M=7kg, d1=0.85m, m=3.6kg) and solving for d2:

7*0.85 = (7 + 3.6)*d2, we get d2 = 0.85*7/10.6 ≈ 0.56m (rounded).

So, the cat can walk about 0.56m to the right of sawhorse B before the plank starts to tip.

Learn more about Static Equilibrium here:

https://brainly.com/question/29316883

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The value of 1.65 meters is the maximum distance the cat can walk to the right of sawhorse B before the plank tips.

We need to set up the conditions for static equilibrium and rotational equilibrium.

The plank has mass M = 7.00 kg and its center of mass is located at d₁ = 0.850 m to the left of sawhorse B.

The cat has a mass of 3.6 kg and is initially at a distance d₂ = 1.11 m to the right of sawhorse B where the plank starts to tip.

To find the tipping point, we need the sum of moments about sawhorse B to equate to zero upon tipping.

Rotational equilibrium condition:

Στ = 0 = (M * g * d₁) - ([tex]m_{cat[/tex] * g * d₂)

Where g is the acceleration due to gravity.
Substituting back in the appropriate values, we have:

(7.00 kg * 9.8 m/s² * 0.850 m) = (3.6 kg * 9.8 m/s² * d₂)

Simplifying, (7 * 0.850) = (3.6 * d₂)

Thus,
d2 = (7 * 0.850 / 3.6) = 1.65 m

Therefore, the cat can walk a maximum distance of 1.65 m to the right of sawhorse B before the plank tips.

As matter changes state from gas to liquid, which of these statements is true?

Answers

Answer:

it is condensing , intermolecular forced are getting stronger

Explanation:

condensation is gas to liquid and intermolecular forces are attaction and liquid molecules are colser together so they have more intermolecular forces hope this helps god bless

What is the difference between systolic and diastolic pressure?

Answers

Answer:

The difference between the systolic and the diastolic pressure is the pulse

Explanation:

Systolic blood pressure is the top number of the maximum pressure your heart exerts while beating (systolic pressure),

and the bottom number is the amount of pressure in your arteries between beats (diastolic pressure).

The numeric difference between your systolic and diastolic blood pressure is called your pulse pressure.

Hence systolic - diastolic = pulse

Answer:

Pulse pressure

Explanation:

Blood pressure readings are given in two numbers, upper and lower limit.

- The upper limit is the maximum pressure your heart exerts while beating, also called systolic pressure.

- The lower is the amount of pressure in your arteries between beats, also called diastolic pressure.

- The numerical difference between systolic and diastolic pressure is called the pulse pressure.

- For example, if your resting blood pressure is 120/80 millimeters of mercury (mm Hg).

                  systolic pressure = 120 mm Hg

                  diastolic pressure = 80 mm Hg

                  Pulse pressure = 120 - 80 = 40 mm Hg

The volume V of a fixed amount of a gas varies directly as the temperature T and inversely as the pressure P . Suppose that V= 42 cm^3 . when T = 84 kelvin and P = kg/cm^2 . Find the volume when T=185 kelvin and P = 10 kg/cm^2

Answers

Complete question:

The volume V of a fixed amount of a gas varies directly as the temperature T and inversely as the pressure P . Suppose that V= 42 cm^3 . when T = 84 kelvin and P = 8 kg/cm^2 . Find the volume when T=185 kelvin and P = 10 kg/cm^2

Answer:

The final volume of the gas is 74 cm³

Explanation:

Given;

initial volume of the gas, V₁ = 42 cm³

initial temperature of the gas, T₁ =  84 kelvin

initial pressure of the gas, P₁ = 8 kg/cm²

final volume of the gas, V₂ = ?

final temperature of the gas, T₂ = 185 kelvin

final pressure of the gas, P₂ = 10 kg/cm²

From the statement given in the question, we formulate mathematical relationship between Volume, V, Temperature, T, and Pressure, P.

V ∝ T ∝ ¹/p

[tex]V =k \frac{T}{P}[/tex]

where;

k is constant of proportionality

make k subject of the formula

[tex]k = \frac{VP}{T} \\\\Thus, \frac{V_1P_1}{T_1} = \frac{V_2P_2}{T_2} \\\\V_2= \frac{V_1P_1T_2}{P_2T_1} \\\\V_2= \frac{42*8*185}{10*84} \\\\V_2 =74 \ cm^3[/tex]

Therefore, the final volume of the gas is 74 cm³

Answer:

V =  74 cm^3

Explanation:

Solution:-

- The volume V of a fixed amount of a gas varies directly as the temperature T and inversely as the pressure P. Expressing the Volume (V) in terms of Temperature (T) and (P):

                                      V ∝ T , V ∝ 1 / P

- Combine the two relations and equate the proportional relation with a proportionality constant:

                                      V = k * (T / P)

Where, k: The proportionality constant:

- Using the given conditions and plug in the given relation of volume V:

             Suppose that V= 42 cm^3 . when T = 84 kelvin , P = 8 kg/cm^2          

                                       k = V*P / T

                                       k = 42*8 / 84

                                       k = 4 kg cm / K

- Use the proportionality constant and evaluate Volume V for the following set of conditions:

                       T=185 kelvin and P = 10 kg/cm^2    

                                     V = 4*( 185 / 10 )

                                     V =  74 cm^3            

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