what is brightness. help asap

Answers

Answer 1

Answer:

The subjective visual sensation related to the intensity of light emanating from a surface or from a point source.


Related Questions

why does a balloon filled with hydrogen rises up only to a certain height​

Answers

Answer: they will rise up because hydrogen is lighter in density and it's weight is lower when it's in the air

Explanation:

Answer:

hydrogen is less dense and its weight is also less than the air.

Explanation:

A wire is placed between the poles of a horseshoe magnet. There is a current in the wire in the direction shown, and this causes a force to act on the wire.

Answers

The answer in the picture

Which musical instruments produce lower pitches

Answers

Answer:

bigger instruments make lower pitches

Explanation:

bass drums and other large instruments have low sounds because they're so big. the smaller the instrument is, the higher pitch it's going to have

Answer:

It is mostly the Bass instruments because they use mouthpieces while the wind instrument use reeds and make a higher pitched sounds

Explanation:

Band

What happens when a sound wave passes from water into air

Answers

Answer:

Explanation:

Sounds travel faster in object having high density proportion or matter. This is because particles vibrates and causing the other particle near to as well vibrate. Hence, when sound is moving from a higher dense medium like Water, the rate of traveling is high compare to it moving in air with less dense.

A tuning fork is vibrating the air around it. What best describes the waves produced by the tuning fork?

Answers

Answer:

The water particles move in the same direction as the vibrating source of the sound wave. ... What best describes the waves produced by the tuning fork? mechanical, because the vibrating tuning fork makes air molecules around it vibrate. A wave is produced in a Slinky as shown.

Explanation:

Answer:

mechanical, because the vibrating tuning fork makes air molecules around it vibrate

Explanation:

If two similar large plates each of area having surface charge density is +a and -b are separated by a distance d in air find the expression for the potential difference and capacitance between them

Answers

Answer:

a. V = (a - b)d/2ε₀ b. 2ε₀A/d

Explanation:

a. The potential difference between the plates

Using Gauss' law, we first find the electric field between the plates

ε₀∫E.dA = Q where Q = charge enclosed, E = electric field

Now Q = [a +(-b)]A = (a - b)A where + a and -b are the surface charge densities of the plates and A is the area of the plates.

ε₀∫E.dA = Q

ε₀∫EdAcos0 + ε₀∫EdAcos0 = (a - b)A

ε₀E∫dA + ε₀E∫dA = (a -b)A

ε₀EA + ε₀EA = (a -b)A

2ε₀EA = (a -b)A

E = (a - b)/2ε₀

We now find the potential difference, V between the plates from

V = ∫E.dl

V =E∫dl

V = Ed  where ∫dl = d the distance between the plates.

V = (a - b)d/2ε₀

b. The capacitance between them

Capacitance C = Q/V

= (a - b)A ÷ (a - b)d/2ε₀

= 2ε₀A/d

Ed biked home from school in 400 seconds. His home is located 2000 m south of the school. What was his velocity?

Answers

[tex]answer = 5 \: \: metre \: per \: second\\ distance = 2000 \: m \\ time = 400 \: seconds \\ velocity = \: \frac{distance \:t ravelled}{time \: taken} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{2000}{400} \\ \: \: \: \: \: \: \: \: \: = 5 \: metre \: per \: second \\ hope \: it \: helps[/tex]

An injured monkey sits perched on a tree branch 9 m above the ground, while a wildlife veterinarian is kneeling down in the bushes 90.0 m away attempting to subdue the monkey with a tranquilizer gun. The vet knows that the moment the gun fires, the monkey will be frightened and fall down from the branch. At what angle up from the ground must the veterinarian aim the gun so that the tranquilizer dart will hit the falling monkey? Given the angle, what is minimum speed at which the tranquilizer dart must leave the gun to still hit the monkey?

Answers

Answer:

The hunter should aim directly at the perched monkey because the tranquilizer dart will fall away from the line sight at the same rate that the monkey falls from its perch.

Tan theta = 9 / 90 = .1      so theta = 5.71 deg

The time for the monkey to reach the ground is

t = (2 h / g)^1/2 = (18 / 9.8)^1/2 = 1.36 sec

So the horizontal speed of the dart must be at least

Vx = 90 m / 1.36 sec = 66.4 m/s

Vx = V cos theta

V = 66.4 m/s / cos 5.71 = 66.7 m/s

The angle of projection of the tranquilizer dart is 5.7⁰

The horizontal speed of the tranquilizer dart is 66.5 m/s

The given parameters;

vertical position of the monkey, y = 9 mhorizontal position of the veterinarian, x = 90

The angle of projection of the tranquilizer dart is calculated as;

[tex]tan(\theta) = \frac{y}{x} \\\\tan(\theta) = \frac{9}{90} \\\\tan(\theta) = 0.1\\\\\theta = tan^{-1}(0.1)\\\\\theta = 5.71 ^0[/tex]

The speed of the tranquilizer dart is calculated as;

X = v₀ₓt

where;

t is the time to reach maximum height

X is the horizontal displacement = 90 m

The time to reach maximum height is calculated as;

[tex]h = v_0_yt + \frac{1}{2} gt^2\\\\h = 0 + \frac{1}{2} gt^2\\\\h = \frac{1}{2} gt^2\\\\t = \sqrt{\frac{2h}{g} } \\\\t = \sqrt{\frac{2\times 9}{9.8} } \\\\t = 1.36 \ s[/tex]

The horizontal speed of the tranquilizer dart is calculated as;

[tex]X = v_0cos(\theta) \times t\\\\90 = v_0\times cos(5.71) \times 1.36\\\\90 = 1.353 v_0\\\\v_0= \frac{90}{1.353} \\\\v_0 = 66.5 \ m/s[/tex]

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HELLO PLZ HELP
Write the properties of brake fluid

Answers

Answer:

Explanation:

If you look at the chemistry behind most brake fluid, it comes from the combination of various types of glycols, which are basically a mixture of non-petroleum and other alcohol-based fluids. After a mixing process, the chemical name gets shortened to “polyglycol”. In addition, there are also high-grade silicone-based fluids, which cannot be mixed with any other type of fluid. So whether it's used in the brake or clutch system, it's important to understand the differences between these common types of brake fluid.

The brake fluid must maintain specific properties. Our brakes can get hot, sometimes up to 1200 degrees, so the fluid needs a high boiling point. Also, because our vehicles experience seasons just as we do, it’s important to have low freezing point as well. On top of maintaining both extremes, it's designed not to damage any rubber components in the brake system.

As a result, the chemical properties found in most brake fluids can permanently dull or damage paint. So be sure to handle with care and be quick to clean any accidental overspills. Brake fluid is hydroscopic, meaning it has a natural tendency to absorb moisture. And over enough time the added moisture can result in corrosion build up or a decreased boiling point. It’s never a bad idea to change your brake fluid every couple of years and try not to leave your reservoir cap off any longer than needed

Answer: high operation temperatures, good low-temperature and viscosity-temperature properties, physical and chemical stability, protection of metals from corrosion, inactivity with respect to mechanical rubber articles, and lubricating effect

Hope this helps

Which statements best describe X-rays?

Answers

Answer:x rays are electromagnetic waves.

x rays are transverse waves

x rays travel at the speed of light

Explanation:

Which quantity Has the same unit as potential difference

Answers

Answer:

Voltage.

Explanation:

A student claims that water's polarity is the reason it has a high specific heat. What method could the student use to test his claim? Perform research to see if other polar molecules have high specific heat Measure how much energy it takes to increase the temperature of water by one degree Mix water with an acid and test the new specific heat Determine how dissolving salt in water affects the specific heat

Answers

Answer:

B

Explanation:

The method used by the student to test his claim is  determine how dissolving salt in water affects the specific heat. The correct option is fourth.

What is specific heat?

The specific heat is the amount of heat required to change the temperature by 1°C. It is denoted by C.

A student claims that water's polarity is the reason it has a high specific heat.

Polarity is determined by the salt dissolved in water. So, to determine how dissolving salt in water affects the specific heat is best method.

Thus, the fourth option is correct.

Learn more about specific heat.

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Differents between foundamental quantity and derived quantities

Answers

Answer:

fundamental quantity can simply be defined as an independent quantity while derived quantity is dependent i.e. the derive their quantities from the fundamental

If a transformer doubles its input voltage, what is the current in the secondary coil if the primary coil is 10 A.

Answers

Answer:

20Amp

Explanation:

Using the transformer formula

Vs/Vp = Ns/Np = Ip/Is

Vs/Vp = Ip/Is

Vp is the primary voltage = input voltage

Vs is the secondary voltage = output voltage

Ip is the current in the primary coil

Is is the amount of current in the secondary coil.

If the transformer doubles its input voltage Vp, its output voltage Vs will be

decreased by 2 but the output current will be doubled

Given the input current Ip = 10A, the current in the secondary coil (output current) will be doubled i.e Is = 2(10) = 20A

The current in the secondary coil be "50 A". To understand the calculation, check below.

Current and Voltage

According to the question,

Current in primary coil, [tex]I_{in}[/tex] = 10 A

We know the relation,

Power = [tex]V_{in} I_{in}[/tex] = [tex]V_{out} I_{out}[/tex]

then,

→ [tex]V_{in} I_{in}[/tex] = [tex]V_{out} I_{out}[/tex]

By substituting the values,

   [tex]V_{in}[/tex] × 10 = 2 [tex]V_{in} I_{out}[/tex]

By applying cross-multiplication,

           10 = 2 [tex]I_{out}[/tex]

         [tex]I_{out}[/tex] = [tex]\frac{10}{2}[/tex]

                = 5 A

Thus the response above is correct.

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A wave is sent down a thick rope that is attached to a thinner rope. What happens when the wave reaches the junction? Explain in words, or draw a diagram.

Answers

Answer:

A fraction of the wave will be reflected at the junction and the remainder will be transmitted through the junction into the thin rope

Explanation:

When the junction of the thin and the thick rope is reached by the wave, the wave behaves in the following two ways;

1) A fraction of the incident wave from the thick rope to the junction/boundary of the thin rope will be reflected back to in the direction of the thick rope with a lower amplitude and upright

2) A fraction of the incident wave from the thick rope to the junction/boundary of the thin rope will be transmitted through the thin rope such that the transmitted pulse on the thin rope will have an higher amplitude than that of the thick rope due to the available energy in the wave pulse and the lesser weight of the thin rope.

The atomic number of a nucleus decreases during which nuclear reactions?

A. Nuclear fission and alpha decay
B. Nuclear fusion and beta decay (positron emission)
C. Nuclear fission and beta decay (electron emission)
D. Nuclear fusion and alpha decay

Answers

The atomic number of a nucleus decreases during:

A. Nuclear fission and alpha decay

What happens in alpha decay?

Alpha decay is an atomic rot process where a shaky core changes to one more component by shooting out a molecule made out of 2 protons and 2 neutrons. This catapulted molecule is known as an alpha molecule and is just a helium core.

It changes or 'rots' into an alternate nuclear core, with a mass number that is decreased by four and a nuclear number that is diminished by two.

Thus, option A is correct.

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if a rock has a speed of 12 m/s as it hits the ground, from what height did it fall assuming the speed was zero.its mass is 50 kg

Answers

Answer:

a=9.8 ms−2 12^2=0^2+2×9.8×H

H=7.35m

Explanation:

To find the height the following formula should be used: v2=u2+2aH

Assuming this occurs on earth,

Answer:

7.3 m

Explanation:

A car has a kinetic energy of 1.9 × 103 joules. If the velocity of the car is decreased by half, what is its kinetic energy?

Answers

Answer:

475 J

Explanation:

Kinetic energy is calculated by one half of the product of mass and velocity squared or expressed as:

KE = 1/2 (mv²)

We calculate as follows:

KE1 = 1/2 (mv²) = 1.9 * 10^3 joules

KE2 = 1/2 (m(v/2)²) = 1/2 (mv²/4)

KE2 =  1.9 * 10^3 joules / 4 = 475 J

Describe how a change in resistance would affect the current in a circuit.

Answers

Explanation:

The relation between potential difference, current and resistance flowing in a circuit is given by using Ohm's law. It can be given by :

V = IR

[tex]I=\dfrac{V}{R}[/tex]

Resistance opposes the flow of electric current in the circuit. It means that, if resistance is more, less current will flow through the circuit.

a vector points 12.0 units along the x-axis and 9.00 units along the y-axis. find the magnitude of the vector

Answers

Explanation:

R = [tex]\sqrt{(12.0)^{2} + (9.00)^{2}}[/tex] = 15 UNIDADES

2Objects 1 and 2 attract each other with a electrostatic force of 18.0 units. If the charge of Object 1 is one-fourth the original value AND the charge of object 2 is tripled AND the distance separating Objects 1 and 2 is halved, then the new electrostatic force will be _____ units.

Answers

Answer:

The new force becomes 3 times of the initial force.

Explanation:

Let q₁ and q₂ are two charged particles. The force between them is given by :

[tex]F=\dfrac{kq_1q_2}{r^2}\ ......(1)[/tex]

If [tex]q_1'=\dfrac{q_1}{4}[/tex]

and

[tex]q_2'=3q_2[/tex]

Also, r' = r/2

New force,

[tex]F'=\dfrac{kq_1'q_2'}{r'^2}[/tex]

Putting all the above values,

[tex]F'=\dfrac{k\dfrac{q_1}{4}3q_2}{(r/2)^2}\\\\F'=3\times \dfrac{kq_1q_2}{r^2}\\\\F'=3F[/tex]

So, the new force becomes 3 times of the initial force.

Please explain it’s in the photo

Answers

Answer:

Since air resistance actually stops vehicles and goes in a vector opposite to the direction of the vehicle and slows it down. Vehicles would want to make vehicles aerodynamic. Many cars bump into air molecules therefore making air resistance. Aerodynamic cars will lesser the allowance of bumping into said molecules. Thats why cars like to cut down on air resistance

Air resistance is friction.  

-- Friction steals kinetic energy.

-- A car gets kinetic energy by burning gasoline, and uses the kinetic energy to get where it needs to go.  

-- If anything steals the car's kinetic energy, then the car has to burn more gasoline to get where it needs to go.

-- Gasoline costs money.

-- Anything that steals a car's kinetic energy costs you more money to operate the car.

(Another thing that takes kinetic energy away from the car is the car's brakes. The driver uses the brakes when he WANTS to slow down or stop, so it's not stealing, but it still costs kinetic energy and money.)

Maggie is a member of her school’s environmental club and is interested in recycling. She asks the question, “How does exposure to the environment affect recyclable plastics?”

What best describes why and how Maggie should change her question to make it a better scientific question?

The answer to the question leads to a testable hypothesis, so the question should be changed to prevent testing.
The question involves giving an opinion about recycling, so it should be changed to rely only on facts.
The focus of the question is too broad, so it should be narrowed to a single environmental factor.
The results are too uncertain, so the question should be changed to one that has a known outcome.

Answers

Answer:

C

Explanation:

Environmental factors provides ambiguity a particular one could be studied to see how it affects recyclable plastics.

The space shuttle is accelerated off its launch pad to a velocity of 525 m/s in 18.0 seconds.
What is its average acceleration?

Answers

Answer: 29.17m/s^2

Explanation:

Given the following :

Velocity = 525 m/s

Time = 18 seconds

Acceleration = change in Velocity with time

Using the motion equation:

v = u + at

Where v = final Velocity

u = Initial Velocity and t = time

Plugging our values

525 = 0 + a × 18

525 = 18(a)

a = 525 / 18

a = 29.166666

a = 29.17 m/s^2

A curium-242 (Z= 96) can be produced by positive-ion bombardment when an alpha particle collides with which of the following nuclei? Note: A neutron is also a product of this bombardment, in addition to the curium-242.
A. Pu -239
B. U -239
C. Am-241
D. Cf-249
E. Pu-241

Answers

Answer:

A. Pu -239

Explanation:

An isotope is an element with the same atomic number but different mass number. most isotope are unstable, having short half life.

Curium-242 is an isotope produced when Plutonium 239 is bombarded by an alpha particle. This reaction between Plutonium 239 and alpha particle gives curium-242, neutron and a high amount of energy as the products.

Curium oxidizes easily, and it is a dangerous metal which can cause cancer initiation when absorbed by biological materials e.g bones or tissue.

what activities belong at the top of the physical activity pyramid

Answers

Answer: Cut down on watching tv, sitting down for more than 30 minutes at a time, and playing video games.

Explanation:

A 0.50 kilogram ball is held at a height of 20 meters. What is the kinetic energy of the ball when it reaches halfway after being released?
A.
49 joules
B.
98 joules
C.
1.0 × 102 joules
D.
1.1 × 102 joules

Answers

Answer:

A

Explanation:

Use the conservation of energy formula to calculate the velocity of the ball when it reaches the halfway point (10m down). Then, use your calculated value to obtain the kinetic energy.

Answer:

A. 49 on Plato

Explanation:

Its the right one trust me .

what is light rays ?​

Answers

Answer:

A light ray is a line (straight or curved) that is perpendicular to the light's wavefronts

Explanation:

Have a great day.

Benda setinggi 3 cm diletakkan pada jarak 10 cm di depan cermin cekung yang berjari-jari


kelengkungan 10 cm. Tentukan:


 Jarak bayangan


 Perbesaran bayangan


 Sifat bayangan

Answers

Answer:

a) Shadow distance

10 cm in front of the mirror.

b) Zoom in the shadow

The shadow formed is the same height as the object and is placed also at the centre of curvature of the mirror as shown in the attached image to this solution.

c) The nature of the shadow

The shadow formed is real, inverted, same size as the object and formed at the centre of curvature.

Explanation:

English Translation

Objects as high as 3 cm are placed at a distance of 10 cm in front of a concave mirror with 10 cm curvature. Determine:

a) Shadow distance

b) Zoom in the shadow

c) The nature of the shadow

Solution

The mirror equation is given as

(1/f) = (1/v) + (1/u)

f = focal length of the mirror = (radius of curvature)/2 = 10/2 = 5 cm

v = image distance = ?

u = object distance = 10 cm

We can then calculate the shadow' s distance from the mirror thus

(1/5) = (1/v) + (1/10)

(1/v) = 0.2 - 0.1 = 0.1

v = (1/0.1) = 10 cm

b) Zoom in the shadow

Since the object is placed at the centre of curvature, as shown in the attached image, the image is formed at a point of intersection of rays. The image formed is the same height as the object and is placed also at the centre of curvature of the mirror.

c) The nature of the shadow

Since the mirror is a concave mirror, the image is real and formed in front of the mirror. The image is also inverted and formed at the centre of curvature of the mirror.

Hope this Helps!!!

What’s the When the temperature increases the viscosity of the liquids ??? Hurry someone plz help

Answers

Answer:

Decreases

Explanation:

Viscosity is inversely proportional to temperature

i.e. η ∝ [tex]\frac{1}{T}[/tex]

Where η is coefficient of viscosity and T is temperature,

Which means that when temperature increases, viscosity decreases and vice versa.

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(SOLVE AND CHECK) Ronald needs a morning breakfast drink that will give him at least 390 calories. Orange juice has 130 calories in 8oz. How many ounces does he need to drink to reach his calorie goal? Write the set of real numbers x less than 6 in set builder notation Honey Corporation, a merchandising company, reported the following results for January:Number of units sold 5,800Selling price per unit $892Unit cost of goods sold $517Variable selling expense per unit $31Total fixed selling expense $152,600Variable administrative expense per unit $48Total fixed administrative expense $390,200Cost of goods sold is a variable cost in this company.a. Prepare a traditional format income statement for January.b. Prepare a contribution format income statement for January. The plan which settled therepresentation issue in the newConstitution was theA. Virginia PlanB. New Jersey PlanC. Great Compromise