18. Magnesium is a silvery-grey metal. When heated in air it reacts with oxygen burning with a bright flame to form a white powder called magnesium oxide. From the paragraph identity a) TWO elements (2 marks)​

Answer:

1. A

2. B

Explanation:

Sound are mechanical waves that are highly dependent on matter for their propagation and transmission.

Sound travels faster through solids than it does through either liquids or gases.

Wavelength can be defined as the distance from one peak to the next peak of a waveform. This distance is also equal to the distance from one trough of a wave to another.

Diffraction is a wavelength property that makes it possible for sound to be heard around a bend. Thus, it's a property that causes a change in the direction of a wave as it travels through or around a barrier (obstacle) in its path.

Simply stated, diffraction involves the bending of waves around small obstacles with their dimensions smaller than or approximately equal to the wavelength of the sound wave.

On the other hand, reflection can be defined as a phenomenon which typically involves a change in the direction of a wave (bounces back) as it falls on a surface.

Hence, reflection is the property of sounds which animals such as bats use to detect their paths as they navigate from one point to another. This phenomenon is generally referred to as echolocation and it typically involves the use of reflection (echo) of sound to gain information about the nature and location of surrounding objects.

Answer:

Student C

Explanation:

order from heaviest to lightest is...

9 kg (A) , 8000g (8 kg) (D) , 2800g (2.8kg) (B), 2 kg (C)

Answer:

the energy produced in a body due to its motion is kinetic energy.

energy produced in a body due to its position is potential energy.

Explanation:

kinetic energy is the energy possessed by a body in motion

Potential energy is the energy possessed by a body by virtue of its position with respect to a reference level

Answer:

[tex]T=62.9*10^{-9}[/tex]

Explanation:

From the question we are told that:

Index of refraction of Rinestones [tex]\gamma_1 =1.5[/tex]

Index of refraction of silicon [tex]\gamma_2 =2.0[/tex]

Wavelength  [tex]\lambda=576nm=576*10^{-9}[/tex]

Let each layer have thickness T

Therefore

Total Thickness =2T

Generally the equation for  Constructive interference is mathematically given by

[tex]2T=(m+0.5)\frac{l\lambda}{\gamma_2}[/tex]

Where

 [tex]M=0[/tex]

 [tex]2T=(0+0.5)\frac{576*10^{-9}}{2*2.0}[/tex]

 [tex]T=62.9*10^{-9}[/tex]

Answer:

D

Explanation:

Let's analyze each option.

A "Multiple copies of the stored data take up very little space."

This is actually true, and it is a positive aspect, as stored digital data does not need any "physical space", it only needs memory and not a lot of it.

So storing data digitally is way more efficient than storing analog data.

B: "They lose quality when they are copied several times."

The data shouldn't change when it is copied, so you should not see a lose in quality.

C: "Stored data are made up of only two different values."

True, but as we know, we can define a lot of things with only two values (zeros and ones), so this is not really a disadvantage.

D: "They are vulnerable to hackers and viruses."

This is true, when you store your data digitally you become vulnerable to hackers stealing your data, so you need to get informatic security in order to protect your data. The same thing with viruses, if you have all your data stored in a given device, and the device becomes infected, there is a chance that you just lost all your data, so you need to have multiple backups of your important information, and again, some protection against viruses.

The correct option is D.

Answer:

D

trust me i just did it

Explanation:

Answer:

Refer to the attachment!~

Answer:

34 kg is the answer to the question

Answer:

ya bestie Anda benar terima kasih nanti sekarang selamat tinggal

Answer:

a. 0.41 m

b. 5.72 m/s

c. i. For part (a), I chose the hand as the reference level since the penny was thrown from the hand and the height of the penny at the hand is zero and also, it is easier to calculate from a zero reference level.

ii. For part (b), I chose the ground as the reference level since the height of the penny above the ground is positive and the height of the penny when the penny hits the ground is zero and also, it is easier to calculate from a zero reference level.

d. 5.72 m/s

Explanation:

a. Use energy to find how high the penny goes above your hand before stopping.

Taking the hand as the ground level, and from the law of conservation of energy, the total mechanical energy at the hand, E equals the total mechanical energy when the penny stops in the air, E'.

E = E'

U + K = U' + K' where U = initial potential energy at hand level = mgh where h = height at hand level = 0, K = initial kinetic energy at hand level = 1/2mv² where v = speed at hand level = 2.85 m/s, U' = final potential energy at stopping level = mgh' where h' = height at stopping level, K = final kinetic energy at stopping level = 1/2mv'² where v = speed at stopping level = 0 m/s (since the penny momentarily stops)

So, U + K = U' + K'

mgh + 1/2mv² = mgh' + 1/2mv'²

substituting the values of the variables into the equation, we have

mg(0) + 1/2m(2.85 m/s)² = mgh' + 1/2m(0 m/s)²

0 + 1/2m(8.1225 m²/s²) = mgh' + 0

m(4.06125 m²/s²) = mgh'

h' = 4.06125 m²/s² ÷ g

h' = 4.06125 m²/s² ÷ 9.8 m/s²

h' = 0.41 m

(b) The penny then falls to the floor, 1.26 m below your hand. Use energy to find its speed just before it hits the floor.  

Taking the hand as the ground level, and from the law of conservation of energy, the total mechanical energy when the penny stops in the air, E'  equals the total mechanical energy on the ground, E"

E' = E"

U' + K' = U" + K" where U' = initial potential energy at stopping level = mgh" where h' = height at stopping level = height of penny above hand, h' + height of hand above ground = 0.41 m + 1.26 m = 1.67 m, K = initial kinetic energy at stopping level = 1/2mv'² where v = speed at stopping level = 0 m/s (since the penny momentarily stops), U = final potential energy at ground level = mgh₁ where h₁ = height at ground level = 0, K = final kinetic energy at ground level = 1/2mv"² where v" = speed at ground level,

So, U' + K' = U' + K'

mgh" + 1/2mv'² = mgh₁ + 1/2mv"²

substituting the values of the variables into the equation, we have

mg(1.67 m) + 1/2m(0 m/s)² = mg(0) + 1/2mv"²

1.67mg + 0 = 0 + 1/2mv"²

1.67mg = 1/2mv"²

1.67g = 1/2v"²

v"² = 2(1.67g)

v" = √[2(1.67g)]

v" = √[2(1.67 m × 9.8 m/s²)]

v" = √[2(16.366 m²/s²)]

v" = √[32.732 m²/s²)]

v" = 5.72 m/s

(c) Explain your choice of reference level for parts (a) and (b).

i. For part (a), I chose the hand as the reference level since the penny was thrown from the hand and the height of the penny at the hand is zero and also, it is easier to calculate from a zero reference level.

ii. For part (b), I chose the ground as the reference level since the height of the penny above the ground is positive and the height of the penny when the penny hits the ground is zero and also, it is easier to calculate from a zero reference level.

(d) Choose a different reference level and repeat part (b)

Taking the hand as the ground level, and from the law of conservation of energy, the total mechanical energy when the penny stops in the air, E'  equals the total mechanical energy on the ground, E"

E' = E"

U' + K' = U" + K" where U' = initial potential energy at stopping level = mgh' where h' = height at stopping level = 0.41 m, K = initial kinetic energy at stopping level = 1/2mv'² where v' = speed at stopping level = 0 m/s (since the penny momentarily stops), U = final potential energy at ground level = mgh₁ where h₂ = height of hand above the ground level = height of ground below hand = -1.26 m(it is negative since the ground is below the hand), K = final kinetic energy at ground level = 1/2mv"² where v = speed at ground level,

So, U' + K' = U' + K'

mgh' + 1/2mv'² = mgh₂ + 1/2mv"²

substituting the values of the variables into the equation, we have

mg(0.41 m) + 1/2m(0 m/s)² = mg(-1.26 m) + 1/2mv"²

0.41mg + 0 = -1.26 mg + 1/2mv"²

0.41mg + 1.26mg = 1/2mv"²

1.67mg = 1/2mv"²

1.67g = 1/2v"²

v"² = 2(1.67g)

v" = √[2(1.67g)]

v" = √[2(1.67 m × 9.8 m/s²)]

v" = √[2(16.366 m²/s²)]

v" = √[32.732 m²/s²)]

v" = 5.72 m/s

Explanation:

A hydrometer sinks more in a lighter liquid

Answer:

Speed = 1.6 m/s

Explanation:

Formula,

Speed = Distance ÷ Time

Answer:

I don't know 11 but in no. 10,

The ans is 3.66

Total distance = 10m+30m+15m = 55m

Total time = 5secs+7secs +3secs =15secs

Av speed = d/t =55/15 = 3.66 m/s

[tex]\\ \sf\longmapsto 35\%\:of 11[/tex]

[tex]\\ \sf\longmapsto 35\%\times 11[/tex]

[tex]\\ \sf\longmapsto \dfrac{35}{100}\times 11[/tex]

[tex]\\ \sf\longmapsto \dfrac{385}{100}[/tex]

[tex]\\ \sf\longmapsto 3.85KJ[/tex]

[tex]\\ \sf\longmapsto 3850J[/tex]

Answer:

The dimension is L

Explanation:

Dimension analysis is a method of representing quantities majorly with respect to some fundamental quantities of mass (M), length (L), time (T).

A sphere has a definite volume which relates to its radius by:

V = [tex]\frac{4}{3}[/tex][tex]\pi[/tex][tex]r^{3}[/tex]

In this equation [tex]\pi[/tex] is a dimensionless quantity, and the unit of v is [tex]m^{3}[/tex].

But, metre is a measure of length, thus it has a dimension of L.

So that,

[tex]m^{3}[/tex] ≅ [tex]L^{3}[/tex]

Then,

[tex]L^{3}[/tex] = [tex]r^{3}[/tex]

Find the cube root of both sides to have,

r = L

Therefore, the dimension of the radius of a sphere is L.

Answer:

0.6 resistance

Answer:

condensation?

Explanation:

Answer:

C) only part of the bandwidth of the AM signal is amplified, causing some of the sideband information to be lost and distortion results.

Explanation:

Selectivity is the ability of a receiver to respond only to a specific signal on a wanted frequency and reject other signals nearby in frequency.

If a receiver is overly selective, only part of the bandwidth of the AM signal is amplified, causing some of the sideband information to be lost and distortion results. Whereas, if a receiver is underselective, the receiver can pick different signals on different frequencies at the same time.

Answer:

total distance dibide by total time

Answer:

E = 62.72 J

Explanation:

Given that,

The mass of a ball, m = 4 kg

The teacher raised the lawn bowling ball to a height of 1.6 meters before they released it.

We need to find the gravitational potential energy of the ball.

We know that,

E = mgh

Where

g is acceleration due to gravity

So,

E = 4 kg × 9.8 m/s² × 1.6 m

E = 62.72 J

So, the gravitational potential energy of the ball is equal to 62.72 J.

Answer:

False you dont repaint your hamster.

Explanation:

LOL

Answer:

I don't agree

Explanation:

Atoms have 3 subatomic particles protons, electrons and neutrons,

Answer:

Explanation:

These Hooke's Law problems are tricky. Here's what we need to know that clears up the problem entirely. The final and also the max speed of the block will be reached at the point where the potential energy of the system is 0. So the equation we need, namely,

[tex]KE+PE=\frac{1}{2}kA^2[/tex] can be simplified down to

[tex]KE=\frac{1}{2}kA^2[/tex] and we solve this first for KE:

[tex]KE=\frac{1}{2}(85)(.30)^2[/tex] and, paying NO attention whatsoever to significant digits here (because if you did the answer you get is not one of the choices)

KE = 3.825 J.  Now we can use that value of kinetic energy and solve for the speed we need:

[tex]KE=\frac{1}{2}mv^2[/tex] so

[tex]3.825=\frac{1}{2}(.50)v^2[/tex] so

[tex]v=\sqrt{\frac{2(3.825)}{.50} }[/tex] so

v = 3.91 m/s

Explanation:

Q7Answer=If light meets a rough surface, each ray obeys the law of reflection. However, the different parts of the rough surface point in different directions, so the light is not all reflected in one direction. Instead, the light is reflected in all directions. This is called diffuse scattering .

Explanation:

1. if an object sjnks in one liquid and floats on another liquid it implies that the density of second liquid is greater than the density of first liquid

Answer:

E" =  Q/4πε₀√[(x² + R²)]³(x - (L - x)/√[(L - 2x)L/(x² + R²) + 1]³})

Explanation:

The electric field due to a charged ring of radius R at a distance x from the center of the ring when the axis of the ring is located on the x - axis is

E = Qx/4πε₀[√(x² + R²)]³

Since the rings are separated by a distance L, the electric field at point x due to the second ring is E' = -Q(L - x)/4πε₀[√((L - x)² + R²)]³. It is negative since it points in the negative x - direction.

So, the resultant electric field at x is E" = E + E' = Qx/4πε₀[√(x² + R²)]³ + {-Q(L - x)/4πε₀[√((L - x)² + R²)]³}

E" =  Qx/4πε₀√[(x² + R²)]³ - Q(L - x)/4πε₀√[((L - x)² + R²)]³

E" =  Q/4πε₀(x/√[(x² + R²)]³ - (L - x)/√[((L - x)² + R²)]³})

E" =  Q/4πε₀(x/√[(x² + R²)]³ - (L - x)/√[(L² - 2Lx + x² + R²)]³})

E" =  Q/4πε₀(x/√[(x² + R²)]³ - (L - x)/√[(L - 2x)L + (x² + R²)]³})

E" =  Q/4πε₀√[(x² + R²)]³(x - (L - x)/√[(L - 2x)L/(x² + R²) + 1]³})

So, the electric field at points along the x axis is

E" =  Q/4πε₀√[(x² + R²)]³(x - {(L - x)/√[(L - 2x)L/(x² + R²) + 1]³})

Answer:

a. Energy = 28800000 Joules

b. Energy = 8 Kwh

c. Cost = $4

Explanation:

Given the following data;

Power = 1000 Watts

Time = 8 hours

Cost = $0.5 per KWh

Conversion:

1 hour = 60 * 60 = 3600 seconds

8 hour = 8 * 3600 = 28800 seconds

a. To find much electrical energy, in joules;

Energy = power * time

Energy = 1000 * 28800

Energy = 28800000 Joules

b. To find how much energy is that in kilowatt hours;

Energy = power * time

Energy = 1000 * 8

Energy = 8000 Watt-hour = 8000/1000 = 8 Kwh (1 Kilowatts is equal to 1000 watts).

c. To calculate the cost of using this heater;

Cost = 8 * 0.5

Cost = $4

Câu trả lời:

C. 60 m

Giải trình:

Cho rằng:

Tốc độ tại A, u = 5m / s

Tốc độ tại B, v = 15m / s

Độ dài quãng đường, AB =?

Tổng thời gian di chuyển = 6 giây

Hãy tính gia tốc, a:

a = (v - u) / t

a = (15 - 5) / 6

a = 1,667 m / s²

Từ :

v² = u² + 2aS

Trong đó, S = khoảng cách

15² = 5² + 2 (1.667 * S)

225 = 25 + 3,334S

225 - 25 = 3,334S

200 = 3,334S

S = 200 / 3,334

S = 59,98 m

S = 60 m