"One of the main projects being carried out by the Hubble Space Telescope is to measure the distances of galaxies located in groups dozens of millions of lightyears away. What method do astronomers use with the Hubble to find such distances

Answers

Answer 1

Answer:

finding Cepheid variable and measuring their periods.

Explanation:

This method is called  finding Cepheid variable and measuring their periods.

Cepheid variable is actually a type of star that has a radial pulsation having a varying brightness and diameter. This change in brightness is very well defined having a period and amplitude.

A potent clear link between the luminosity and pulsation period of a Cepheid variable developed Cepheids as an important determinants of cosmic criteria for scaling galactic and extra galactic distances. Henrietta Swan Leavitt revealed this robust feature of conventional Cepheid in 1908 after observing thousands of variable stars in the Magellanic Clouds. This in fact turn, by making comparisons its established luminosity to its measured brightness, allows one to evaluate the distance to the star.

Answer 2

Answer:

finding Cepheid variable and measuring their periods.

Explanation:

This method is called  finding Cepheid variable and measuring their periods.

Cepheid variable is actually a type of star that has a radial pulsation having a varying brightness and diameter. This change in brightness is very well defined having a period and amplitude.

A potent clear link between the luminosity and pulsation period of a Cepheid variable developed Cepheids as an important determinants of cosmic criteria for scaling galactic and extra galactic distances. Henrietta Swan Leavitt revealed this robust feature of conventional Cepheid in 1908 after observing thousands of variable stars in the Magellanic Clouds. This in fact turn, by making comparisons its established luminosity to its measured brightness, allows one to evaluate the distance to the star.


Related Questions

Dash is standing on his frictionless skateboard with three balls, each with a mass of 155 g, in his hands. The combined mass of Dash and his skateboard is 65 kg. How fast should dash throw the balls forward if he wants to move backward with a speed of 1.04 m/s?

Answers

Answer:

1.0326 m/s

Explanation:

mass of each ball, m = 155 g = 0.155 kg

mass of Dash and his skateboard, M = 65 kg

Speed of skateboard moving backward, v = 1.04 m/s

Let the speed of the balls in forward direction is u.

By using the conservation of momentum

Momentum in backward direction = Momentum in forward direction

(M + 3m) x u = M x v

(65 + 3 x 0.155) x u = 65 x 1.04

65.465 u = 67.6

u = 1.0326 m/s

Thus, the speed of balls in forward direction is 1.0326 m/s.

Final answer:

If Dash wants to move backward with a speed of 1.04 m/s, he should throw the balls forward with a velocity of about -0.996 m/s.

Explanation:

To calculate the velocity with which Dash should throw the balls to move backward, we can use the principle of conservation of momentum. According to this principle, the total momentum before throwing the balls should be equal to the total momentum after throwing the balls.

The initial momentum of Dash and his skateboard can be calculated as the product of their combined mass and velocity. The final momentum can be calculated as the sum of the momentum of Dash and his skateboard moving backward, and the momentum of the balls moving forward.

Using the formula for momentum (momentum = mass * velocity), we can set up the equation: (65 kg) * (-1.04 m/s) = (68 kg) * V, where V is the velocity with which Dash should throw the balls.

Solving for V, we find that Dash should throw the balls forward with a velocity of about -0.996 m/s to move backward with a speed of 1.04 m/s.

A 0.89 kg ball is moving horizontally with a speed of 3.8 m/s when it strikes a vertical wall. The ball rebounds with a speed of 1.3 m/s. What is the magnitude of the change in linear momentum of the ball?

Answers

Answer:

The change in momentum, p = -4.539 kg-m/s

Explanation:

It is given that,

Mass of the ball, m = 0.89 kg

Initial speed of the ball, u = 3.8 m/s

Final speed of the ball, v = -1.3 m/s (as it rebounds)

Let p is the change in linear momentum of the ball. We know that the linear momentum is equal to the product of mass and velocity. It is given by :

[tex]p=m(v-u)[/tex]

[tex]p=0.89\ kg\times ((-1.3)-3.8)\ m/s[/tex]

p = -4.539 kg-m/s

So, the change in linear momentum of the ball is 4.539 kg-m/s. Hence, this is the required solution.

The reason for this correlation is not fully understood, but most astronomers take it to mean that the evolution of normal and active galaxies must be very closely connected. By observing galaxies at different distances and corresponding look-back times, astronomers have concluded that supermassive black holes were created as galaxies merged during (or just before) the quasar epoch 10-12 billion years ago. How did galactic mergers contribute to the development of supermassive black holes?

Answers

Answer: The hierarchical formation model suggests that galaxies may have been formed  by subsequent mergers of smaller galaxies and that today each galaxy houses at least  a supermassive black hole.

Explanation: During a fusion of galaxies, the stars that composes it suffer the tidal force, intensifying your action as the galaxies approaching. When two galaxies merges themselves, the astronomers believes that they loss a huge part of their mass, forming the supremassive black hole, that stays in the middle of the galaxie.

The supermassive black holes are originated from the evolution of high mass stars. They were formed by huge clouds of gas or clusters of millions of stars that collapsed on their own gravity when the universe was still much younger and denser.

An ideal refrigerator extracts 500 joules of heat from a reservoir at 295 K and rejects heat to a reservoir at 493 K. What is the ideal coefficient of performance and how much work is done in each cycle?

Answers

Answer:

C.O.P = 1.49

W = 335.57 joules

Explanation:

C.O.P = coefficient of performance = (benefit/cost) = Qc/W ...equ 1 where C.O.P is coefficient of performance, Qc is heat from cold reservoir, w is work done on refrigerator.

Qh = Qc + W...equ 2

W = Qh - Qc ...equ 3 where What is heat entering hot reservoir.

Substituting for W in equ 1

Qh/(Qh - Qc) = 1/((Qh /Qc) -1) ..equ 4

Since the second law states that entropy dumped into hot reservoir must be already as much as entropy absorbed from cold reservoir which gives us

(Qh/Th)>= (Qc/Tc)..equ 5

Cross multiple equ 5 to get

(Qh/Qc) = (Th/Tc)...equ 6

Sub equ 6 into equation 4

C.O.P = 1/((Th/Tc) -1)...equ7

Where Th is temp of hot reservoir = 493k and Tc is temp of cold reservoir = 295k

C.O.P = 1/((493/295) - 1)

C.O.P = 1.49

To solve for W= work done on every cycle

We substitute C.O.P into equ 1

Where Qc = 500 joules

1.49 = 500/W

W = 500/1.49

W = 335.57 joules

As part of his flight training, a student pilot was required to fly to an airport and then return. The average speed to the airport was 90 mph, and the average speed returning was 120 mph. Find the distance between the two airports if the total flying time was 7 hours.

Answers

-- We don't know the distance yet, but we have to call it something so that we can work with it.  

I have chosen to represent the distance with the symbol ' D ' .

-- The time it took him to GO to the airport was D/90 hours.

-- The time it took him to RETURN from the airport was D/120 hours.

-- The total time for the round trip was (D/90 + D/120).

The Arithmetic:

Total 2-way time = (D/90) + (D/120)

Common denominator:   (D/90) + (D/120)  =  210D / 10,800

Total flying time given:  210D / 10,800  =  7 hours

Multiply each side by 10,800:  210D = 75,600

Divide each side by 210:  D = 360 miles

Check:

Going . . . 360 miles / 90 mph = 4 hours

Returning . . . 360 miles / 120 mph = 3 hours

Total time . . . 4 hrs + 3 hrs  =  7 hrs yay!

Note:

You can't just average the two numbers and call that his average speed for the round trip.

-- Average of 90 mph and 120 mph is (1/2)(90+120) = 105 mph

-- His actual average speed was (720mi/7hr) = 102.86 mph

The distance between the two airports is 735 mile.

What is speed?

Speed is distance travelled by the object per unit time. Due to having no direction and only having magnitude, speed is a scalar quantity With SI unit meter/second.

given parameters:

The average speed to the airport; v₁ = 90 mph.

The average speed returning; v₂ =  120 mph.

Total time taken; t = 7 hours.

We have to find, the distance between the two airports if the total flying time was 7 hours: s = ?

The average speed of flight; v = (v₁+v₂)/2 = (90 +120)/2 mph. = 105 mph.

So,  the distance between the two airports if the total flying time was 7 hours: s = vt = 105 mph × 7 hr = 735 m.

Hence,  the distance between the two airports is 735 mile.

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An object is dropped from the top of a tall building. At 2 seconds, it is 64 feet from the top of the building. At 4 seconds, it is 256 feet from the top of the building. What is the average rate the object was traveling in the interval between 2 and 4 seconds?

Answers

Answer:

96.21 ft/s

Explanation:

To solve this, you only need to use one expression which is:

Vf² = Vo² + 2gh

g = 9.8 m/s²

However, this exercise is talking in feet, so convert the gravity to feet first:

g = 9.8 * 3.28 = 32.15 ft/s²

Vo is zero, because it's a free fall and in free fall the innitial speed is always zero. With this, let's calculate the speed at 2 seconds, with a height of 64 ft, and then with the 256 ft:

V1 = √2*32.15*64

V1 = 64.15 ft/s

V2 = √2*32.15*256

V2 = 128.3 ft/s

So the average rate is:

V = 128.3 + 64.15 / 2

V = 96.22 ft/s

A jet aircraft is traveling at 201 m/s in horizontal flight. The engine takes in air at a rate of 44.1 kg/s and burns fuel at a rate of 3.28 kg/s. The exhaust gases are ejected at 669 m/s relative to the aircraft. Find the thrust of the jet engine. Answer in units of N.

Answers

Answer:22,833.12 N

Explanation:

Given

Velocity of Jet [tex]v=201 m/s[/tex]

Velocity of Exhaust gases [tex]u=669 m/s[/tex]

Rate of intake of air [tex]\frac{\mathrm{d} M_a}{\mathrm{d} t}=44.1 kg/s[/tex]

Rate at which Fuel is burned is [tex]\frac{\mathrm{d} M_f}{\mathrm{d} t}=3.28 kg/s[/tex]

Rate of change of mass in Rocket [tex]\frac{\mathrm{d} M}{\mathrm{d} t}=\frac{\mathrm{d} M_a}{\mathrm{d} t}+\frac{\mathrm{d} M_f}{\mathrm{d} t}=44.1+3.28=47.38 kg/s[/tex]

Thrust on Rocket is given by

[tex]F=\frac{\mathrm{d} M}{\mathrm{d} t}u-\frac{\mathrm{d} M_a}{\mathrm{d} t}v[/tex]

[tex]F=47.38\times 669-44.1\times 201[/tex]

[tex]F=31,697.22-8864.1=22,833.12 N[/tex]

A crate is sitting in the center of a flatbed truck. As the truck accelerates to the east, the crate moves with it, not sliding on the bed of the truck. In what direction is the friction force exerted by the bed of the truck on the crate?

Answers

Answer:East

Explanation:

Given

The truck is accelerating towards east along with crate and crate is not sliding.

Friction Force on the crate will act towards the east as friction Force always opposes the motion of an object. Also in this case, if friction force is absent then crate would have moved backward.

Thus static Friction will help the crate to move with truck.

                 

A 120-kg object and a 420-kg object are separated by 3.00 m At what position (other than an infinitely remote one) can the 51.0-kg object be placed so as to experience a net force of zero from the other two objects?

Answers

Answer:

1.045 m from 120 kg

Explanation:

m1 = 120 kg

m2 = 420 kg

m = 51 kg

d = 3 m

Let m is placed at a distance y from 120 kg so that the net force on 51 kg is zero.

By use of the gravitational force

Force on m due to m1 is equal to the force on m due to m2.

[tex]\frac{Gm_{1}m}{y^{2}}=\frac{Gm_{2}m}{\left ( d-y \right )^{2}}[/tex]

[tex]\frac{m_{1}}{y^{2}}=\frac{m_{2}}{\left ( d-y \right )^{2}}[/tex]

[tex]\frac{3-y}{y}=\sqrt{\frac{7}{2}}[/tex]

3 - y = 1.87 y

3 = 2.87 y

y = 1.045 m

Thus, the net force on 51 kg is zero if it is placed at a distance of 1.045 m from 120 kg.

The product of the frequency and the wavelength of a wave equals the

Answers

Answer: Velocity of the wave

Explanation:

The product of the frequency and the wavelength of a wave equals the Velocity of the wave.

Velocity of the wave has to do with its displacement with respect to time taken for the wave to move from one point to another. This can be measured in meter/second

All of the following statements about the pyramid of biomass are correct EXCEPT: a. Biomass is the total dry mass of the organisms presentb. The base of the pyramid generally represents primary consumersc The amount of biomass at a particular level of the pyramid depends on the amount of energy availabled. Certain toxins tend to become concentrated at the upper levels of the pyramide. Biomass pyramids tend to vary for different ecosystems.

Answers

The correct answer is B. The base of the pyramid generally represents primary consumers.

Explanation

A biomass pyramid is a graphic representation of the biomass present in a unit area of various trophic levels, this graphic representation shows the relationship between biomass and the trophic level that quantifies the biomass available at each trophic level of an energy community at a specific time. In general, an ecosystem is represented in a pyramid in which the primary producers occupy the base of the pyramid because they have more biomass in a unitary area. An example of the organization of a biomass pyramid is an ecosystem in which caterpillars feed on oak trees; In turn, the caterpillars are consumed by a bluebird, which is consumed by a sparrowhawk. In this example, the oak tree is at the base of the biomass pyramid, because it feeds dozens of caterpillars, thanks to its massive biomass, and the sparrowhawk occupies the highest level of the pyramid. Therefore, it is incorrect to affirm that the base of the pyramid generally represents primary consumers, because the primary producers are generally at the base of the pyramid. So, the correct answer is B. The base of the pyramid generally represents primary consumers.

For a science project, you would like to horizontally suspend an 8.5 by 11 inch sheet of black paper in a vertical beam of light whose dimensions exactly match the paper.
If the mass of the sheet is 0.80g , what light intensity will you need?
Express your answer to two significant figures and include the appropriate units.
I = ________.

Answers

Answer:

I = 3.9 x 10⁷ W/m²

Explanation:

given,

Sheet of black paper dimension = 8.5 x 11 inch

Area of sheet = 8.5 x 11 = 93.5 inch^2

1 inch =0.0254 m

Area = 0.06032 m²

mass of sheet = 0.80 g

Force = m g =  0.8 x 9.8 x 10⁻³ N

                    =  7.84 x 10⁻³ N

speed of light = c = 3 x 10⁸ m/s

Using equation

[tex]F = \dfrac{IA}{c}[/tex]

where I is the intensity of light

[tex]7.84 \times 10^{-3} = \dfrac{I\times 0.06032}{3 \times 10^8}[/tex]

[tex]2.352 \times 10^{6} = I\times 0.06032[/tex]

[tex]I = \dfrac{2.352 \times 10^{6}}{0.06032}[/tex]

I = 3.9 x 10⁷ W/m²

Intensity of the light is equal to I = 3.9 x 10⁷ W/m²

You open the refrigerator in your room and put in a case of room-temperature root beer. After an hour, the root beer is ice cold. If your room air did not exchange any heat with the outdoor air during that time, the room air will be________.

Answers

Answer:

warmer

Explanation:

The law of conservation of energy tells us that energy cannot be created or destroyed, it can be transferred or converted from one from to another. In this question when the beer that is at room temperature is put in the fridge, it loses some heat energy. This heat energy is not destroyed, the fridge through  multiple processes eventually releases this heat to the room through pipes at the back which is why they are normally warm. the heat from the food inside is expelled to the room. It is not lost.

Determine the COP of a heat pump that supplies energyto a house at a rate of 8000 kJ/h for each kW of electric power it draws. Also, determine the rate of energy absorption from the outdoor air.

Answers

Final answer:

The Coefficient of Performance (COP) of the heat pump is 2.22 and the rate at which it absorbs energy from the outdoor air is 1222 Watts.

Explanation:

The quality of a heat pump is judged by how much energy is transferred by heat into the warm space compared with how much input work is required. This measure is referred to as the Coefficient of Performance (COP). To calculate the COP of a heat pump which supplies energy at a rate of 8000 kJ/h for each kW of electrical power it draws, we have to convert all the units to the same base, which in this case will be watts (W).

1 kW = 1000 W and 8000 kJ/h = (8000*1000) J/3600 s = 2222 W

Hence, using the formula for the COP of the heat pump: COPhp = Qh/W, we substitute the given values and we get: COPhp = 2222W/1000W = 2.22. This means that for every 1 Watt of electricity the heat pump uses, it generates 2.22 Watts of heat for the house.

Additionally, the rate of energy absorption from the outdoor air is the difference between the rate of heat supply to the house and the electric power drawn, which is 2222W - 1000W = 1222W.

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The COP of the heat pump is 2.22, and the rate of energy absorption from the outdoor air is 1.22 kJ/s.

Determining the COP of a Heat Pump

The Coefficient of Performance (COP) of a heat pump is defined as the ratio of heat energy delivered to the heated space (Qh) to the energy input (W). In this case, we are given that the heat pump supplies 8000 kJ/h for each kW of electric power it draws.

Firstly, convert the supplied energy and power input to consistent units. Since 1 kW = 1 kJ/s, we have:

Energy supplied, Qh = 8000 kJ/h = 8000 / 3600 kJ/s = 2.22 kJ/s

Power input, W = 1 kW = 1 kJ/s

Apply the COP formula:

COP = Qh / W = 2.22 kJ/s / 1 kJ/s = 2.22

To determine the rate of energy absorption from the outdoor air (Qc), use the energy balance equation:

Qh = Qc + W

Solving for Qc:

Qc = Qh - W = 2.22 kJ/s - 1 kJ/s = 1.22 kJ/s

Thus, the COP of the heat pump is 2.22 and the rate of energy absorption from the outdoor air is 1.22 kJ/s.

Small blocks, each with mass m, are clamped at the ends and at the center of a rod of length L and negligible mass. Compute the moment of inertia of the system about an axis perpendicular to the rod and passing through (a) the center of the rod and (b) a point one-fourth of the length from one end

Answers

Answer:

Answered

Explanation:

a) Two balls are at a distance of L/2 from the axis of rotation and one block at the center. ( center of rod).

therefore,

[tex]I=2\times m\frac{L}{2}^2[/tex]

[tex]I= \frac{1}{2}mL^2[/tex]

b) two balls at a distance L/4 at the from the axis and 1 ball at a distance 3L/4 from the from the axis.

[tex]I= 2\times m\times(L/4)^2 + m(\frac{3L}{4})^2[/tex]

= [tex]\frac{1}{16} mL^2(2+9)= \frac{11}{16}mL^2[/tex]

The moment of inertia of the system about an axis perpendicular to the rod and passing through the center of the rod is 1/2mL².

How to calculate the moment of inertia?

It should be noted that the moment of inertia of the system about an axis perpendicular to the rod and passing through the center of the rod will be calculated thus:

I = 1/2 × mL²/2

I = 1/2mL²

Also, the moment of inertia of the system about an axis perpendicular to the rod and passing through a point one-fourth of the length from one end will be:

I = 2 × m × (L/4)² + m(3L/4)²

I = (2 + 9)1/16mL²

I = 11/16mL²

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If a system is isolated, the total energy of the system ________. If a system is isolated, the total energy of the system ________. depends on the work into the system. increases constantly. depends on the work out of the system. is constant. decreases constantly.

Answers

Answer:

Is constant.

Explanation:

Isolated systems cannot exchange energy or matter outside the borders of the system.

Final answer:

An isolated system is a system that has no exchange of matter or energy with its environment. Despite changes in internal energy due to heat transfer or work done within the system, the total energy of an isolated system remains constant. The total energy of the system encompasses its kinetic energy, potential energy, and internal energy.

Explanation:

If a system is isolated, the total energy of the system is constant. This concept is part of the conservation of energy principle. An isolated system is one in which there is no exchange of matter or energy with the external environment. For instance, an ideal gas inside a thermally insulating and immoveable container would be an isolated system.

Though the internal energy of the system could change through processes such as heat transfer or work done on the system, the total energy remains unchanged. In other words, while energy itself might change forms within the system, the sum of kinetic, potential, and internal energy doesn't alter.

Consider a situation where heat transfer puts 159.00 J into the system, which raises the internal energy by 9.00 J. Despite how the energy was acquired, the system’s final state relates to its internal energy. Therefore, the initial and final total energy of the system remains same.

It's important to note that while total energy remains constant in isolated systems, in open systems (which can exchange energy and/or matter with its surroundings), the total energy can increase or decrease based on the work in/out of the system.

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Where does the heat come from that drives this convection current in the mantle

Answers

Answer:

Earth's interior (Core)

Explanation:

The earth is comprised of 3 distinct layers namely the Core, the Mantle and the Crust, which are divided based on their composition as well as density.

The core of the earth is extremely very hot where the inner core remains solid and outer core acts a liquid. It is mainly comprised of iron, nickel and other siderophile elements.

A large amount of heat (energy) is radiated from this core region towards the surface of the earth. Due to this, the mantle rocks forms magma that creates the convection currents, where the hot and less dense magma rises upward and the cool and denser magma sinks to the bottom. This occurs continuously, as a result of which the lithospheric plates are forced to move over the less dense layer of asthenosphere.

Thus, the heat energy that drives the convection current in the mantle is provided from the interior (core) of the earth.

Answer:

earths core

Explanation:

A 1/10th scale model of an airplane is tested in a wind tunnel. The reynolds number of the model is the same as that of the full scale airplane in air. The velocity in the wind tunnel is then

Answers

The Reynolds number expresses the ratio between inertia forces and viscous forces. Hence, For the reynold number of the model to be the same as that of the full scale airplane in air, the velocity in the wind tunnel would be the same as the velocity of the full scale airplane.

The Reynolds number is related using the formula :

Re = ρVD / μ

Re = Reynolds number ; ρ = density ; V = velocity ; D = pipe diamater ; μ = Fluid viscosity

In other to obtain the same value Reynolds number value for both the original and model airplane, only the value of density used in the wind tunnel for the model airplane should be changed while other parmaters remain the same.

The air density used in the wind tunnel would be increased by the factor used for the model airplane, in this case 10.

Therefore, the value of velocity in the wind tunnel has to be the same as the velocity of the original airplane.

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A jet aircraft is traveling at 291 m/ s in horizontal flight. The engine takes in air at a rate of 63.8 kg/s and burns fuel at a rate of 1.21 kg/s. The exhaust gases are ejected at 667 m/s relative to the aircraft. Find the thrust of the jet engine and the delivered power.

Answers

Answer:

thrust = 24795.87 N

Power  = 7.215 MW

Explanation:

given data

The speed of the jet v = 291 m/s

The air intake is dMa/dt = 63.8 kg/s

The fuel burn rate is dMf/dt = 1.21 kg/s

The speed of the exhaust gas is u = 667 m/s

to find out

thrust of the jet engine and the delivered power

solution

first we get here rate of mass change in the rocket that is  

rate of mass change dM/dt = 63.8  + 1.21

rate of mass change dM/dt = 65.01 kg/s

and

The thrust on the rocket will be here

thrust T = (dM/dt) u - (dMa/dt) v       ..................1

thrust T = (65.01) 667 - (63.8) 291

thrust T = 24795.87 N

and

now the power of the rocket will be here

Power  = speed × thrust        .................2

Power  = 291  × 24795.87

Power  = 7.215 MW

Which wavelength produces fluorescence? Why do you think this wavelength produces fluorescence while the other does not?

Answers

Answer:

Long wavelength

Explanation:

Wavelengths that corresponds to the bands of blue and red are strongly absorbed whereas the wavelengths that lie in the mid-range corresponds to green light that are absorbed weakly.

Fluorescence produced is always directed towards longer wavelengths of the spectra as compared to the corresponding spectra for absorption.

Two football players collide head-on in midair while trying to catch a thrown football and cling together. The first player is 94 kg and has an initial velocity of 6 m/s, while the second player is 116 kg and has an initial velocity of -5 m/sn the next three parts, (d) through (f), justify that friction could be ignored compared to the forces of collision by considering the change in momentum of the first player. Let's assume that the collision lasts for 10ms. Calculate the force on the first player by the second player during the collision

Answers

Final answer:

The combined velocity of the two football players just after they collide and cling together is calculated to be 0.80 m/s in the direction of the first player's original motion, using the law of conservation of momentum.

Explanation:

To determine the velocity just after impact when two football players collide and cling together, we can use the law of conservation of momentum. The initial momentum of the system is the sum of the momentum of each player before they collide. For the first player with a mass of 95.0 kg and velocity of 6.00 m/s, and the second player with a mass of 115 kg and velocity of -3.50 m/s, the total initial momentum is:

(95.0 kg × 6.00 m/s) + (115 kg × -3.50 m/s) = 570 kg·m/s - 402.5 kg·m/s = 167.5 kg·m/s.

After the collision, the two players cling together and thus have a combined mass of 95.0 kg + 115 kg = 210 kg. The final velocity of the two players clinging together can be found by dividing the total initial momentum by the combined mass:

Final velocity = Total initial momentum / Combined mass = 167.5 kg·m/s / 210 kg = 0.80 m/s.

Therefore, the combined velocity of the two football players just after the collision is 0.80 m/s in the direction of the first player's initial motion.

Which feature or process is unique to nuclear power plants when compared to conventional coal-burning power plants?

Answers

Answer:

Control rods

Explanation:

Control rods is unique to nuclear power plants as they are mainly used in nuclear reactors to stabilize the rate of fission of plutonium or uranium. They are usually composed of chemical elements such as cadmium, silver, boron, and indium.

Answer:

Control rods

Explanation:

Control rods are used to control the rate of nuclear chain reaction in nuclear reactors. The reactivity of the nuclear reactor is greatly affected by the distance of control rods inserted and number of control rods inserted. Control rods control the rate of fission of uranium, etc., in a nuclear reactor

A motor drives a disk initially at rest through 25.9 rotations in 5.0 s. Assume the vector sum of the torques caused by the force exerted by the motor and the force of friction is constant. The rotational inertia of the disk is 4.0 kg⋅m2. When the motor is switched off, the disk comes to rest in 12 s.
A.)What is the magnitude of torque created by the force of friction?
B.)What is the magnitude of torque caused by the force exerted by the motor?

Answers

Answer

given,

rotation of disk is equal to(θ) = 25.9

time taken = 5 s

moment of inertia of disk = 4 Kg.m²

disk come to rest in = 12 sec

a)  θ = 2 π x 25.9

    θ = 162.73 rad

    using equation of rotational motion

     θ =  ω₀t + 0.5 α t²

     162.79 =  0 + 0.5 x α x 5²

      α = 13.02 rad/s²

total torque acting

 [tex]\tau_{frictional} + \tau_{rotational} = I \alpha[/tex]

 [tex]\tau_{frictional} + \tau_{rotational} = 4\times 13.02[/tex]

 [tex]\tau_{frictional} + \tau_{rotational} =52.08[/tex]

again using the rotational equation

   [tex]\omega_f - \omega_i = \alpha\ t[/tex]

   [tex]\omega_f -0 = 13.02 \times 5[/tex]

   [tex]\omega_f = 65.1\ rad/s[/tex]

when only friction is acting angular acceleration

   [tex]\omega_f - \omega_i = \alpha\ t[/tex]

   [tex]0 -65.1 =\alpha\ 12[/tex]

   [tex]\alpha= -5.425\ rad/s^2[/tex]    

now torque due to friction

  [tex]\tau_{frictional} =- 4 \times 5.425[/tex]

  [tex]\tau_{frictional} =-21.7\ Nm[/tex]

now,

 [tex]-21.7+ \tau_{rotational} =52.08[/tex]

 [tex] \tau_{rotational} =73.78\ Nm[/tex]

How does the force of gravity between two bodies change when the distance between them doubles?

Answers

Answer:

If the distance is doubled, the force of gravity between the two bodies is one-fourth as strong as before

Explanation:

The force of gravity between two bodies depends on the mass and distance. But we will focus on distance since that's what the question asks

Therefore, the force of gravity decreases as distance between the bodies increases.

Water has a very high specific heat capacity when compared to most other common materials. In fact, ethyl alcohol has a specific heat that is only about that of water, whereas the specific heat of lead is about that of water. Suppose that you have equal‑mass samples of each material and that each sample is at the same initial temperature. You then carefully transfer the same amount of heat into each sample and measure the resulting final temperature of each. Rank the final temperature of each sample from highest to lowest.

Answers

Answer:

Lead, Ethyl alcohol and water.

Explanation:

Specific heat capacity of a substance can be define as the quantity of heat that is absorbed by a substance needed to change the temperature of a unit mass of one kilogram of the substance by one kelvin

The ranking of the final temperature of the substances from highest to lowest is;

Lead > Ethyl alcohol > Water

We are told that water has a very high specific heat capacity.

Specific heat capacity of ethyl alcohol is 2.46 J/g.K which is about 2/5 of water

Specific heat capacity of lead = (1/30) of water

Now, the specific heat capacity is the heat required to raise the temperature of a substance.

This means that the higher the specific heat capacity, the lower the final temperature.

Now, from the samples given, we can say that;

Water has the highest specific heat capacity Ethyl alcohol has the second highest specific heat capacityLead has the lowest specific heat capacity.

Thus, lead will have the highest final temperature followed by ethyl alcohol, then water.

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A wind turbine is initially spinning at a constant angular speed. As the wind's strength gradually increases, the turbine experiences a constant angular acceleration of . After making 2870 revolutions, its angular speed is 133 rad/s. (a) What is the initial angular velocity of the turbine? (b) How much time elapses while the turbine is speeding up?

Answers

:Answer:

a. the initial angular velocity = 166.5rad/s

b. t= 135.7seconds

Explanation:

a. v = rw

angular velocity for 2870 rev, w = (2πN)/60 =2*3.142*2870rev)/60 =300.5rad/sec

w₁-w₂ = 300.5 - 133= 166.5rad/s

the initial angular velocity = 166.5rad/s

acceleration = change in velocity / time

b. 1 revolution = 2π

1 rad = 0.159rev

? = 2870 rev

=2870*1)/0.159 = 18050.3rad

the final angular speed = rev/time = rad/time

133 rad/s = 18050.3/t

133t = 18050.3

t= 135.7seconds

A piece of spacecraft debris initially at rest falls to the earth's surface from a height above the earth equal to one-half of the earth's radius. Find the speed at which the piece of debris hits the surface. Neglect air resistance and the gravitational pull of the moon.

Answers

Final answer:

The debris speed on hitting the surface of the Earth can be found by equating potential and kinetic energy, yielding the formula v = √(2GM/R), where G is the gravitational constant, M is Earth's mass, and R is Earth's radius.

Explanation:

The key to solving for the final speed of this piece of debris is utilizing the concepts of energy conservation and gravitational potential energy. When the debris is at a distance equal to half the Earth's radius (R/2) above the surface, all of its energy is potential. At the point it hits the surface, all this potential energy would have been converted to kinetic energy, with negligible loss to thermal or any other types of energy as we are ignoring air resistance and gravitational pull from the moon.

The total energy when the debris is still in the air is given by its gravitational potential energy Pe = -GMm/(R/2), where G is the gravitational constant, M is the Earth’s mass, m is the debris mass, and R is the Earth's radius.

At the point the debris hits the Earth, all its potential energy would have been converted to kinetic energy Ke = ½mv², where v is its velocity on impact.

Equating the initial and final energies, we get -GMm/(R/2) = ½mv². Solving this equation for v (the magnitude of the velocity), we get v = √(2GM/R). This represents the speed of the debris when it hits the Earth's surface.

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Consider a blackbody that radiates with an intensity i1 at a room temperature of 300k. At what intensity i2 will this blackbody radiate when it is at a temperature of 400k?

Answers

Answer:

3.16 i1

Explanation:

T1 = 300 k

I1 = i1

T2 = 400 k

i2 = ?

The intensity is directly proportional to the four powers of the absolute temperature.

I ∝ T^4

So, [tex]\frac{i_{2}}{i_{1}}=\frac{T_{2}^{4}}{T_{1}^{4}}[/tex]

[tex]\frac{i_{2}}{i_{1}}=\frac{400^{4}}{300^{4}}[/tex]

i2 = 3.16 i1

Thus, the intensity becomes 3.16 i1.

A client is receiving an IV solution of sodium chloride 0.9% (Normal Saline) 250 ml with amiodarone (Cordarone) 1 gram at 17 ml/hour. How many mg/minute of amiodarone is infusing? (Enter numeric value only. If rounding is required, round to the nearest tenth.)

Answers

Answer:

1.1mg/min

Explanation:

We are given that

Volume of solution=250 ml

Mass of amiodarone=1 g

Infusion rate=17 ml/hr

We know that

1 g= 1000 mg

Ratio of 1000g:250 ml=[tex]\frac{1000}{25}=4 mg/ml[/tex]

The concentration of solution=4mg/ml

Amiodarone infusing (mg/min)=[tex]\frac{infusion \;rate(ml/hr)\times concentration}{60}[/tex]

Because 1 hr= 60 minute

Amiodarone infusing=1.1mg/m

Hence, 1.1 mg/min of amiodarone is infusing.

The amount of amiodarone infusing per minute is 1.1 mg when calculated from the prescribed dosage of 1 gram in a 250 ml IV solution infused at 17 ml/hour.

The question revolves around the calculation of the amiodarone dosage being infused per minute through an intravenous (IV) therapy. Given the infusion rate of 17 ml/hour and a total amount of 1 gram (1000 mg) of amiodarone in 250 ml of Normal Saline, we can calculate the dosage per minute. First, find the concentration of amiodarone in mg/ml by dividing 1000 mg by 250 ml to get 4 mg/ml. Then, we calculate the amount infused per hour by multiplying this concentration (4 mg/ml) by the infusion rate (17 ml/hour). Finally, divide by 60 minutes to get the dosage per minute.

The calculation steps are as follows:

1. Amiodarone concentration = 1000 mg ÷ 250 ml = 4 mg/ml

2. Amiodarone per hour = 4 mg/ml × 17 ml/hour = 68 mg/hour

3. Amiodarone per minute = 68 mg/hour ÷ 60 minutes/hour = 1.13 mg/minute

The amount of amiodarone infused per minute is therefore approximately 1.13 mg, which rounds to 1.1 mg/minute when rounding to the nearest tenth.

A transverse sinusoidal wave on a string has a period T = 25.0 ms and travels in the negative x direction with a speed of 30.0 m/s. At t = 0, an element of the string at x = 0 has a transverse position of 2.00 cm and is traveling downward with a speed of 2.00 m/s.
(a) What is the amplitude of the wave?
(b) What is the initial phase angle?
(c) What is the maximum transverse speed of an element of the string?
(d) Write the wave equation for the wave.

Answers

Final answer:

The amplitude is 2.00 cm. The initial phase angle, the maximum speed, and the wave equation can be found by substituting the given values into the relevant formulas.

Explanation:

The (a) amplitude of the wave is determined by the maximum displacement from the equilibrium position, which is 2.00 cm.

(b) The initial phase angle can be determined by the equation φ = -arccos(v₁/ωA), where v₁ is the initial speed of the element, ω is the angular frequency, and A is the amplitude. Here, ω=2π/T, T is the period. Therefore, φ = -arccos((-2.00 m/s)/(2π/(25.0 ms)*2.00 cm))

(c) The maximum transverse speed of an element of the string would be ωA, since the speed of the element is highest when it passes through its equilibrium position. Thus, the maximum speed = 2π/(25.0 ms)*2.00 cm.

(d) And lastly, the wave equation for the wave is Y(x,t) = Acos(kx + ωt + φ), where Y is the transverse displacement, A is the amplitude, k is the wave number, ω is the angular frequency, t is time, x is position, and φ is the phase constant. In this case, k = 2π/λ, where λ is the wavelength which can be found by dividing the speed of the wave by the frequency (v/f = λ).

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We determined the wave's amplitude to be approximately 3.33 cm, the initial phase angle to be π/3, and the maximum transverse speed to be about 8.37 m/s. The wave equation was found to be y(x, t) = 0.0333 sin(8.38x + 251.33t + π/3). Step-by-step explanations clarify each part.

Part a :

We start with the transverse wave function: y(x, t) = A sin(kx + ωt + φ). Given that at t = 0 and x = 0, the transverse position y is 2.00 cm, traveling downward with a speed of 2.00 m/s.

First, determine the frequency, and hence the angular frequency ω. The period T is given as 25.0 ms:

ω = 2π/T = 2π/(25.0 x 10⁻³) s ≈ 251.33 rad/s

The transverse speed of the string element is:

dy/dt = -Aω cos(φ) = -2.00 m/s (since it's traveling downward)

Given y(0, 0) = A sin(φ) = 0.020 m:

A = 0.020 m / sin(φ)

Using the transverse speed equation, we get:

-0.25133 A cos(φ) = -2.00 m/s

cos(φ) = 2.00 / (0.25133 A)

From both equations, sin²(φ) + cos²(φ) = 1, solving for A.

A = 2.00 cm x √(1 + (1/0.25133²)) ≈ 3.33 cm

Part b :

sin(φ) = 0.020 / 0.0333 ≈ 0.6

cos(φ) = 2.00 / (251.33 x 0.0333) ≈ 0.8

φ ≈ π/3

Part c :

The maximum transverse speed is given by Aω ≈ 3.33 cm x 251.33 rad/s ≈ 8.37 m/s.

Part d :

The general form of the sinusoidal wave traveling in the negative x-direction is:

y(x, t) = 0.0333 sin(kx + ωt + π/3)

Given that the wave speed v = 30.0 m/s:

k = ω/v = 251.33 rad/s / 30.0 m/s ≈ 8.38 m-1

Wave equation becomes:

y(x, t) = 0.0333 sin(8.38x + 251.33t + π/3)

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