4. How do scientists know that dark matter exists? (1 point)
O They assume that anything invisible has to be dark.
O Something has to be there to form superclusters.
The Redshifts give the dark matter away.
O They observe gravitational lensing bending the light of other objects in space.

Answer:    Vf = Vi + A(t)

Vf= -2+ (-9.8)(5)

Vf = -51 m/s

Explanation:

The final velocity is equal to the initial velocity plus the acceleration multiplied by the time

(-9.8) is used for the acceleration for this question because that is the speed at which things in free fall accelerate when they are on earth

-2 is used as the initial velocity because the ball was thrown in the negative direction which is down.

The time of 5 was given in the question so you can plug it in for time

Answer:

Explanation:

Given:

V₀ = 2 m/s

g = 9.8 m/s²

t = 5 s

____________

V - ?

Axis OX direct vertically down. Then:

V = Vₓ = V₀ₓ + g·t

V = 2 + 9.8*5 = 51 m

Answer:

The value is  \(v = 147.2 \ m/s\)

Explanation:

From the question we are told that

    The force is   \(F = 130 \ N\)

     The linear mass density is  \(\mu = 0.006 \ kg/m\)

Generally the speed of the wave on the string is mathematically represented as  

            \(v = \sqrt{\frac{F}{\mu } }\)

=>        \(v = \sqrt{\frac{130}{0.006} }\)

=>        \(v = 147.2 \ m/s\)

The magnitude of the vector is approximately 35.85 m.

The angle that this vector makes with the positive x-axis is approximately 32 degrees.

To find the magnitude of the vector with components Ax=29 m and Ay=18 m, we use the Pythagorean theorem:

|A| = √(Ax^2 + Ay^2)

|A| = √(29^2 + 18^2)

|A| = √(841 + 324)

|A| = √1165

|A| =  34.13 m

To find the angle that this vector makes with the positive x-axis, we can use the inverse tangent function:

θ = tan^-1(Ay/Ax)

θ = tan^-1(18/29)

θ = 31.82 degrees

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CHECK COMPLETE QUESTION BELOW

you weigh 685 NN on the earth, what would be your weight on the surface of a neutron star that has the same mass as our sun and a diameter of 25.0 kmkm ? Take the mass of the sun to be msmsm_s = 1.99×1030 kgkg , the gravitational constant to be GGG = 6.67×10−11 N⋅m2/kg2N⋅m2/kg2 , and the free-fall acceleration at the earth's surface to be ggg = 9.8 m/s2m/s2 .

Answer:

5.94×10^15N

Explanation:

the weight on the surface of a neutron star can be calculated by below expresion

W= Mg

W= weight of the person

m= mass of the person

g=gravity of the neutron star

But we need the mass which can be calculated as

m= W/g

m= 685/9.81

m= 69.83kg

From the gravitational law equation we have

F= GMm/r^2

G= gravitational constant = 6.67x10⁻¹¹

M= mass of the neutron star = 1.99x10³⁰ kg

r = distance between the person and the surface

Then r can be calculated as = 25/2 = 12.5 km , we divide by two because it's the distance between the person and the surface

g=gravity of the neutron star can be calculated as

g=(6.67×10^-11 ×1.99×10^30)/(12.5×10^3)^2

= 8.50×10^13m/s^2

Then from W= mg we can find our weight

W= 8.50×10^13m/s^2 × 69.83

= 5.94×10^15N

Therefore, weight on the surface of a neutron star is 5.94×10^15N

Answer:

The time taken by the projectile to hit the ground is 6.85 sec.

Explanation:

Given that,

Vertical height of cliff = 230 m

Distance = 300 m

Suppose, determine the time taken by the projectile to hit the ground.

We need to calculate the time

Using second equation of motion

\(s=ut+\dfrac{1}{2}gt^2\)

Where, s = vertical height of cliff

u = initial vertical velocity

g = acceleration due to gravity

Put the value in the equation

\(230=0+\dfrac{1}{2}\times9.8\times t^2\)

\(t=\sqrt{\dfrac{230\times2}{9.8}}\)

\(t=6.85 sec\)

Hence, The time taken by the projectile to hit the ground is 6.85 sec.

1) The force acting on the object during the time interval 0-3 seconds is 1/3 N.

2) The force acting on the object during the time interval 6-10 seconds is -0.5 N.

3) There is no time interval in which no force acts on the object.

(i) Force acting on the object in time interval 0-3 seconds. Force acting on the object is equal to the product of its mass and acceleration, i.e.,F = ma.

In the given velocity-time graph, the acceleration of the object can be determined by determining the slope of the velocity-time graph from 0 to 3 seconds.

Slope = (change in velocity) / (change in time)= (20-0) / (3-0) = 20/3 m/s^2

Acceleration, a = slope= 20/3 m/s^2

Mass of the object, m = 50 g = 0.05 kg

∴ Force acting on the object, F = ma= 0.05 × 20/3= 1/3 N.

Therefore, the force acting on the object during the time interval 0-3 seconds is 1/3 N.

(ii) Force acting on the object in time interval 6-10 seconds. Similar to the first question, the force acting on the object in time interval 6-10 seconds can be determined by determining the acceleration of the object during this time interval.

The slope of the velocity-time graph from 6 seconds to 10 seconds can be determined as follows:

Slope = (change in velocity) / (change in time)= (-20-20) / (10-6) = -40/4= -10 m/s^2 (negative sign indicates that the object is decelerating)

Mass of the object, m = 50 g = 0.05 kg

∴ Force acting on the object, F = ma= 0.05 × (-10)= -0.5 N.

Therefore, the force acting on the object during the time interval 6-10 seconds is -0.5 N.

(iii) Time interval in which no force acts on the object. There is no time interval in which no force acts on the object. This is because, as per Newton's first law of motion, an object will continue to remain in a state of rest or uniform motion along a straight line unless acted upon by an external unbalanced force.In other words, if the object is moving with a constant velocity, there must be a force acting on the object to maintain its motion.

Therefore, there is no time interval in which no force acts on the object.

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The glycerin index predicts the way certain foods affect​ the blood glucose.

The glycemic index is a numerical scale that ranks carbohydrates in foods based on how they affect blood glucose levels compared to a reference food, typically pure glucose  or white bread. Foods with a high glycerin index cause rapid increase in blood sugar levels, while foods with a low glycerin index result in a slower and more gradual increase.

The glycerin index is often used as a tool for managing blood sugar levels, particularly in individuals with diabetes. Foods with a lower glycerin index are generally considered healthier as they provide more sustained energy and have a lesser impact on blood sugar levels.

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Answer:

I'm pretty sure that the answer is C. Hope this helps.

Explanation:

Answer:

Answer is A. Under any conditions

Explanation:

Just got it correct on A p e x

Answer:

can someone please answer this i need this for a mastery test aswell

Explanation:

it would be very appreciated

Answer:

3.45 inches = 8.763e-5 kilometers

At the lowest point on the Ferris wheel, there are two forces acting on the child: their weight of 430 N, and an upward centripetal/normal force with magnitude n; then the net force on the child is

∑ F = ma

n - 430 N = (430 N)/g • a

where m is the child's mass and a is their centripetal acceleration. The child has a linear speed of 3.5 m/s at any point along the path of the wheel whose radius is 17 m, so the centripetal acceleration is

a = (3.5 m/s)² / (17 m) ≈ 0.72 m/s²

and so

n = 430 N + (430 N)/g (0.72 m/s²) ≈ 460 N

Answer:

it will burn up in the Earth's atmosphere.

Explanation:

The structure of the Earth's atmosphere protects the surface from frequent meteoroid strikes. As a meteoroid enters the atmosphere from outer space, it moves at very high speeds. At such speeds, intense amounts of friction and heat result. This process usually causes small meteoroids to burn up in the Earth's atmosphere before ever reaching the surface.

Answer:

the difference between electron, protons and neutrons is the charge they carry. Electrons are charged negative protons are charged negative and neutrons do not carry any charge

Explanation:

the difference between the three are there charge. The electrons are negatively charged, protons are positive and neutrons are electrically neutral.

And they are the 3 main sub atomic particles

The finished compost can be used to enrich soil for planting and gardening. Mix the compost into the soil or use it as a top dressing around plants.

Substances Used to Fill It:

A mixture of "brown" and "green" organic materials such as leaves, grass clippings, fruit and vegetable scraps, coffee grounds, and shredded paper can be used to fill the bin.

Household Items That Can Go in It:

Most fruit and vegetable scraps, eggshells, tea bags, coffee grounds, yard waste such as grass clippings and leaves, and shredded paper can be added to the compost bin. Meat, dairy, and fatty foods should be avoided.

How Long It Takes Before It Is Ready:

The compost should be ready to use in approximately 6 to 12 months, depending on the environmental conditions and the frequency of turning and mixing the compost.

How You Use the Compost:

The finished compost can be used as a nutrient-rich soil amendment for planting and gardening.

Compost Bin Design:

To add household items to your compost bin, simply add any of the following organic materials to the bin: fruit and vegetable scraps, coffee grounds and filters, tea bags, eggshells, yard waste such as leaves and grass clippings, and shredded paper.

Compost is ready to use in this much time:

The compost should be ready to use in approximately 6 to 12 months, depending on the environmental conditions and the frequency of turning and mixing the compost.

Use your compost this way:

The finished compost can be used to enrich soil for planting and gardening. Mix the compost into the soil or use it as a top dressing around plants.

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Answer:

(a) The current needed is 56.92 A

(b) The magnitude of the magnetic field inside the solenoid is 0.134 T

(c) The energy density inside the solenoid is 7.144 kJ/m³

Explanation:

Given;

energy stored in the magnetic field of solenoid, E = 8.1 J

number of turns of the solenoid, N = 620 turns

diameter of the solenoid, D = 6.6 cm = 0.066 m

radius of the solenoid, r = D/2 = 0.033 m

length of the solenoid, L = 33 cm = 0.33 m

Inductance of the solenoid is given as;

\(L= \frac{\mu_o N^2 A}{l}\)

where;

A is the area of the solenoid = πr² = π (0.033)² = 0.00342 m²

μ₀ is permeability of free space = 4π x 10⁻⁷ H/m

\(L= \frac{4\pi*10^{-7} *620^2 *0.00342}{0.33} \\\\L = 0.005 \ H\)

(A). How much current needed

Energy stored in magnetic field of solenoid is given as;

\(E = \frac{1}{2} LI^2\\\\\)

Where;

I is the current in the solenoid

\(E = \frac{1}{2} LI^2\\\\I^2 = \frac{2E}{L}\\\\I = \sqrt{\frac{2*8.1}{0.005}}\\\\ I = 56.92 \ A\)

(B) The magnitude of the magnetic field inside the solenoid

B = μ₀nI

where;

n is number of turns per unit length

B = μ₀(N/L)I

B = (4π x 10⁻⁷)(620/0.33)(56.92)

B = 0.134 T

(C) The energy density (energy/volume) inside the solenoid

\(U_B = \frac{B^2}{2\mu_0} \\\\U_B = \frac{(0.134)^2}{2*4\pi*10^{-7}} \\\\U_B = 7143.54 \ J/m^3\\\\U_B = 7.144 \ kJ/m^3\)

Answer:

The chemical structure of the molecule is responsible for each of these characteristics. The chemical structure is comprised of the bonding angle, the kind of bonds, the size of the molecule, and the interactions that occur among the molecules. Even little changes in the chemical structure of a molecule may have a significant impact on the characteristics of the substance.

Explanation:

Hope it helps:)

The type of decay that has no charge associated with it is gamma decay (option C).

Gamma decay is a nuclear reaction with the emission of a gamma ray. A gamma ray is a high frequency/energy electromagnetic radiation emitted as a consequence of radioactivity.

Gamma rays are waves, not particles. This means that they have no mass and no charge.

This, therefore, suggests that when a gamma ray is emitted, no charge is involved.

Unlike alpha and beta decay that involves +2 and -1 charges respectively.

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Explanation:

Water is wet, in the sense of being a liquid which flows easily, because its viscosity is low, which is because its molecules are rather loosely joined together.

Answer:

Liquid water is not itself wet, but can make other solid materials wet.

Wetness is the ability of a liquid to adhere to the surface of a solid, so when we say that something is wet, we mean that the liquid is sticking to the surface of a material.

Whether an object is wet or dry depends on a balance between cohesive and adhesive forces. Cohesive forces are attractive forces within the liquid that cause the molecules in the liquid to prefer to stick together. Cohesive forces are also responsible for surface tension. If the cohesive forces are very strong, then the liquid molecules really like to stay close together and they won't spread out on the surface of an object very much. On the contrary, adhesive forces are the attractive forces between the liquid and the surface of the material. If the adhesive forces are strong, then the liquid will try and spread out onto the surface as much as possible. So how wet a surface is depends on the balance between these two forces. If the adhesive forces (liquid-solid) are bigger than the cohesive forces (liquid-liquid), we say the material becomes wet, and the liquid tends to spread out to maximize contact with the surface. On the other hand, if the adhesive forces (liquid-solid) are smaller than the cohesive forces (liquid-liquid), we say the material is dry, and the liquid tends to bead-up into a spherical drop and tries to minimize the contact with the surface.

Water actually has pretty high cohesive forces due to hydrogen bonding, and so is not as good at wetting surfaces as some liquids such as acetone or alcohols. However, water does wet certain surfaces like glass for example. Adding detergents can make water better at wetting by lowering the cohesive forces . Water resistant materials such as Gore-tex fabric is made of material that is hydrophobic (water repellent) and so the cohesive forces within the water (liquid-liquid) are much stronger than the adhesive force (liquid-solid) and water tends to bead-up on the outside of the material and you stay dry.

Answer:

Layer C

Explanation:

Hope this helps!

-Liyah<3

Explanation:

F = kx

mg = kx

(20 kg) (10 m/s²) = (1800 N/m) x

x = 0.11 m

The near point of a human eye is about a distance of 25 cm.

The closest distance that an object may be viewed clearly without straining is known as the near point of the eye.

This distance (the shortest at which a distinct image may be seen) is 25 cm for a typical human eye.

The closest point within the accommodation range of the eye at which an object may be positioned while still forming a focused picture on the retina is also referred to as the near point.

In order to focus on an item at the average near point distance, a person with hyperopia must have a near point that is further away than the typical near point for someone of their age.

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Answer:

A saturated vapour is one that is in balance with its own liquid. Space is considered to be unsaturated if it contains fewer vapours than the maximum amount it can retain at a given temperature. Saturated vapour pressure is unaffected by volume, although it rises as temperature rises.

Explanation:

I'm sorry, I'm not able to see the figure you mentioned. Can you please provide more information or context about the figure and the question you have related to it?

Answer:

\(\huge\boxed{\sf P = 10\ Watts}\)

Explanation:

Given:

Energy = E = 200 J

Time = t = 20 s

Required:

Power = P = ?

Formula:

P = E / t

Solution:

P = 200 J / 20 s

P = 10 Watts

\(\rule[225]{225}{2}\)

Hope this helped!

Answer:

20 * .3 = 6N

Explanation:

The impulse on the ball kicked with a force of 20 N force 0.3 s is 6 Ns

From the question given above, the following data were obtained:

Force = 20 N

Time = 0.3 s

The impulse on the ball can be obtained as follow:

\(impulse \: = force \: \times time \\ impulse \: = 20 \: \times \: 0.3 \\\)

Therefore, the impulse on the ball is 6 Ns

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Explanation:

For electromagnetic waves    c = wavelength * frequency

 c = speed of light = 3 x 10^8 m/ s

                                    3 x 10^8 m/s = wl * 33 x 10^9  Hz

                                        wl = .009 m      ( or  9 mm)

If a radar signal that has a frequency of 33 GHz, Then the wavelength of the radar signal is  9 mm.

Wavelength is a fundamental concept in the study of waves, which are disturbances that propagate through space or a medium. It is defined as the distance between two consecutive points in a wave that are in phase, meaning that they have the same position in their respective cycles.

In other words, the wavelength is the spatial period of a wave, which is the distance over which the wave repeats itself. It is commonly represented by the Greek letter lambda (λ) and is measured in meters (m), although it can also be expressed in other units such as nanometers (nm) or micrometers (μm).

Wavelength is a key property of waves, as it determines many of their characteristics and behavior. For example, the wavelength of an electromagnetic wave (such as light or radio waves) determines its color or frequency, and thus its energy and ability to interact with matter. Similarly, the wavelength of a sound wave determines its pitch, and thus its perceived tone and musical quality.

The relationship between wavelength, frequency, and velocity is described by the wave equation, which states that the velocity of a wave is equal to the product of its wavelength and frequency. This relationship is important for understanding how waves behave and interact with their environment, such as when they are reflected, refracted, or diffracted.

So, the wavelength is a crucial concept in the study of waves, as it defines their properties and behavior. It is the distance between two consecutive points in a wave that are in phase, and is measured in meters or other units. The relationship between wavelength, frequency, and velocity is described by the wave equation, which is fundamental to the study of waves in various fields such as physics, engineering, and communication.

Here in the Question,

The wavelength of a radar signal can be calculated using the formula:

wavelength = speed of light/frequency

where the speed of light is approximately 3 x 10^8 meters per second.

Plugging in the given frequency of 33 GHz (33 x 10^9 Hz), we get:

wavelength = 3 x 10^8 / (33 x 10^9)

wavelength = 0.009090909... meters

Therefore, By rounding to the nearest millimeter, the wavelength of the radar signal is approximately 9 mm.

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If the ball is thrown straight up into the air with an initial velocity of 20m/s, it will be in the air for 4.08 s

a = v / t

a = Acceleration

v = Velocity

t = Time

v = 20 m / s

a = 9.81 m / s²

t = 20 / 9.81

t = 2.04 s

This is the time taken to reach the farthest height the ball will raise. It takes the equal amount of time to reach the point from where it was thrown from.

T = 2t

T = Total time taken

T = 2 * 2.04

T = 4.08 s

Therefore, the ball will be in the air for 4.08 s

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The required choice is for both the lines are conductor and conductor.

A conductor is something that easily allows current to flow through it. As an example, consider metal or any other metal. An insulator is something that does not allow current to travel through it. Polyurethane is an example.

Here,
Inside each socket are two pairs of metal strips that are engineered to bend and flex but return to their original shape when pressure is released. Each pair of strips is linked to one of your power lines (either hot or ground).

When you insert the wall plug, springy brass fingers hold the plug prongs, allowing you to connect to your home's electrical system.

Thus, the required choice is for both the lines to be conductor and conductor.

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The braking distance of the car, given the data from the question is 145.784 m

From the question given above, the following data were obtained:

The breaking distance of the car can be obtained as illustrated below:

s = ut + ½at²

s = (60 × 2.44) + (½ × -0.207 × 2.44²)

s = 146.4 + (-0.616)

s = 146.4 - 0.616

s = 145.784 m

From the calculation made above, we can conclude that the breaking distance of the car is 145.784 m

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