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Answer:

neither A nor B

Explanation:

There are a lot of reasons, quite handful of them. About why scientists repeat experiments.

They do so sometimes to persistently verify the results they have gotten. Another reason is so as to be able to study and improve them in other ways.

This is just 2 of the very many reasons why scientists repeat experiments. Remember the popular saying, that practice makes perfect? yeah, that's just it

I hope you understand. Thanks

Answer:

c

Explanation:

Answer:

The task of philosophy, for Plato, is to discover through reason (“dialectic”) the nature of the Forms, the only true reality, and their interrelations, culminating in an understanding of the most fundamental Form, the Good or the One. Aristotle rejected Plato’s theory of Forms but not the notion of form itself. For Aristotle, forms do not exist independently of things—every form is the form of some thing. A …

Explanation:

Answer:

A

Explanation:

Because it is a region in atmosphere that allows an particular wavelength of EMWs to pass through and of the options above only visible light is allowed to pass through

3.56 displacement ( m )

Answer:

oxygen silicon aluminun iron

Complete Question

What mass of aluminum has a total nuclear charge of 2.9 C?

Aluminum has atomic number 13. Suppose the aluminum is all of the isotope with 14 neutrons.

Answer:

The  mass is   [tex]T_m  = 6.252 *10^{-5}\  g[/tex]

Explanation:

From the question we are told that

   The  total nuclear charge is  [tex]q =  2.9 \  C[/tex]

   The  atomic number is  [tex]u  =  13[/tex]

    The number of neutron is  [tex]k  =  14[/tex]

Generally the number of positive charge is mathematically represented as

      [tex]N  = \frac{q}{p}[/tex]

here p is the charge on a single proton with value  [tex]p =  1.60*10^{-19} \  C[/tex]

So      

     [tex]N = \frac{2.9}{1.60*10^{-19}}[/tex]

=>    [tex]N = 1.813*10^{19} \ protons[/tex]

Now since 1 atom contains 13 proton

The  number of atoms present is

        [tex]a =  \frac{1.813*10^{19}}{13}[/tex]

       [tex]a =  1.395 *10^{18} \  atoms[/tex]

Then the number of moles present is mathematically represented as

      [tex]n = \frac{a}{N_k}[/tex]

Where  N_k is the Boltzmann constant with value  

       [tex]N_k  =  6.023*10^{23}[/tex]

So

       [tex]n  =  \frac{1.395 *10^{18}}{ 6.023*10^{23}}[/tex]

        [tex]n = 2.315 *10^{-6}\  moles[/tex]

Generally one mole of aluminum is equal to 27 g

So

 The total  mass of aluminum  is

          [tex]T_m  = n *  27[/tex]

=>        [tex]T_m  = 2.315 *10^{-6}  *  27[/tex]

=>        [tex]T_m  = 6.252 *10^{-5}\  g[/tex]

Answer:

Option B

200 cm

Explanation:

From statistical evidence, the average height of an adult is about 200cm. This is like 2m or 6.56 feet.

Despite the fact that there are some exceptions; with some adults reaching heights of about seven feet, and some dwarfs who stand only about 1 m tall,  most adults only grow to about 200cm in height before they start shrinking due to old age.

Answer:

C. Diffraction

Explanation:

Diffraction is the bending of waves as they pass by a barrier or through an opening. One of the condition for diffraction is that the size of the aperture or obstacle is comparable to the wavelength of light. Fresnel diffraction and Fraunhofer diffraction are two types of diffraction.

Hence, the correct option is (c) "Diffraction".

Answer:

Special relativity.

Explanation:

Einstein's general theory of special relativity describes the relationship

between energy and matter, and is major event in the history

of science.

In 1905, Albert Einstein a noble physicist developed a theory that forms part of the basis of modern physics and one of the major event in the history of science, this theory was known as the theory of special relativity.

The theory of special relativity gives the relationship between space and time for any object that is moving at a uniform speed in a straight line, typically at the speed of light.

Simply stated, the theory of special relativity describes how a change in the speed of an object affect or relate with the measurement of space, time and mass. This ultimately implies that, as an object approach the value of light speed, it gains an infinite amount of mass and as such it is unable to travel faster than light.

The theory of special relativity by Albert Einstein gave birth to one of the most famous equation in science;

[tex]E = mc^2[/tex]

The equation illustrates, Energy equals mass multiplied by the square of the speed of light.

Where; E = Energy.

M = Mass.

C = Speed of light.

From the above equation, we can deduce that the mass of an object increases with speed and that mass is equivalent to energy, thus matter (mass) can be interchanged with energy.

Answer:

Given initial height h¹= 1.44

Final height h²=1.68

So factor increase is 1.68/1.44²= 1.17

Percentage increase will be

1.68-1.44/1.44*100%=16.7%

Answer:

232.641374 mph

Explanation:

A race car has a maximum speed of 0.104km/s

Let X represent the speed in miles per hour

Therefore the speed in miles per hour can be calculated as follows

1 km/s = 2,236.936292 mph

0.104km/s = X

X = 0.104 × 2,236.936292

X = 232.641374

Hence the speed in miles per hour is 232.641374 mph

Speed of the car can be defined by the ratio of distance traveled by time elepsed. The speed of the given car is 233.212 miles/hr.

Speed can be defined by the change in position of an object in a given period of time.

[tex]\bold {Speed = \dfrac {Distance }{Time}}[/tex]

Given here,

The speed of the car is 0.104 km/s

Since 1 km = 0.621

So,  0.104 km = 0.0646

and 1 s = 0.000277

So, the speed of the car in  miles per hour,

[tex]Speed = \dfrac {0.0646 \rm \ miles }{0.000277}\\\\ Speed =233.212 \rm \ miles/hr[/tex]

Therefore, the speed of the given car is 233.212 miles/hr.

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Answer:

An virus

Explanation:

An computer virus can come from websites that try to steal your Information or apps that's not necessarily scanned and protected so that yor computer can be safe from viruses.

A computer may encounter problems or get "ill" for a variety of reasons. The system can become infected with malware and viruses, which can cause performance issues and data loss.

A failing hard drive or defective RAM are examples of hardware issues that can lead to instability and crashes. Overheating can lead to hardware damage or performance deterioration and is frequently brought on by insufficient cooling or clogged air vents.

Systems may become unstable as a result of software conflicts between out-of-date or incompatible programmes.

Electrical problems or power surges can harm components and interfere with proper operation. Computer issues can also be caused by human error, such as inadvertent file deletion or poor configuration.

Thus, a computer can be kept in good condition with routine maintenance, security precautions, and appropriate usage.

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The given expression 3 + 2 ∙ 4 = 3 + (2 ∙ 4) is absoulutely correct so it is True.

Arithmetic operators are four basic mathematical operations in which summation, subtraction, division, and multiplication involve.,

Summation = addition of two or more numbers or variable

For example = 2 + 8 + 9

Subtraction = Minus of any two or more numbers with each other called subtraction.

For example = 4 - 8

Division = divide any two numbers or variable called division.

For example 4/8

Multiplication = to multiply any two or more numbers or variables called multiplication.

For example 5 × 7.

Given,

3 + 2 ∙ 4 = 3 + (2 ∙ 4)

We know that in every calculation we cannot separate multiplication and need to solve them first

So,

3 + 8 = 3 + 8

11 = 11

Hence, 3 + 2 ∙ 4 = 3 + (2 ∙ 4)  is absoulutely correct.

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Answer:

There are eight planets in our Solar System.

Explanation:

Answer:

8

Explanation:

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Answer:

e) electrons are transferred from the rod to the silk.

Explanation:

An initially neutral glass rod contains equal number of electron and proton.

If the rod becomes positively charged  after being rubbed with silk, then the rod must have lost some its electron to the silk since electrons are more mobile than protons, leaving the rod with excess positive charge (protons), and the silk will be negatively charged (excess electron).

Thus, the rod becomes positively charged by transfer of electrons from rod to the silk.

e) electrons are transferred from the rod to the silk.

Answer:i

9E13 ELECTRONS

Explanation:

First we find the number of charges in two hrs

Which is - 2x 7200=- 14400NC

So no of electrons is now q/e

-144x10^-7/-1.6*10^-19

= 9*10^13

Answer:

(A) The maximum height of the ball is 40.57 m

(B) Time spent by the ball on air is 5.76 s

(C) at 33.23 m the speed will be 12 m/s

Explanation:

Given;

initial velocity of the ball, u = 28.2 m/s

(A) The maximum height

At maximum height, the final velocity, v = 0

v² = u² -2gh

u² = 2gh

[tex]h = \frac{u^2}{2g}\\\\h = \frac{(28.2)^2}{2*9.8}\\\\h = 40.57 \ m[/tex]

(B) Time spent by the ball on air

Time of flight = Time to reach maximum height + time to hit ground.

Time to reach maximum height = time to hit ground.

Time to reach maximum height  is given by;

v = u - gt

u = gt

[tex]t = \frac{u}{g}[/tex]

Time of flight, T = 2t

[tex]T = \frac{2u}{g}\\\\ T = \frac{2*28.2}{9.8}\\\\ T = 5.76 \ s[/tex]

(C) the position of the ball at 12 m/s

As the ball moves upwards, the speed drops, then the height of the ball when the speed drops to 12m/s will be calculated by applying the equation below.

v² = u² - 2gh

12² = 28.2² - 2(9.8)h

12² - 28.2² = - 2(9.8)h

-651.24 = -19.6h

h = 651.24 / 19.6

h = 33.23 m

Thus, at 33.23 m the speed will be 12 m/s

Answer:

65 miles per hour

Explanation:

Speed= Distance/Time

Following this formula, we just need to insert the values.

The distance is 125 miles and the time is 2 hours

125=2=65

65 miles per hour

The speed of the car was exactly 125 mi per 2 hours.

In a more familiar unit,  125mi/2hr = 62.5 mi/hr.

Answer:

0.9 Amps

Explanation:

Ohm's law: Voltage = Current x Resistance

Rearrange equation:

Current =Voltage/Resistance

Voltage=6v

In a series circuit the total resistance is the sum of all the resistors so the total resistance = 0.1+0.15+0.2+0.25+6=6.7 Ohms

6/6.7 = 0.9 (1dp) Amps

Because it is a series circuit, the current is the same throughout the entire circuit, all the resistors have a current of 0.9 Amps.

Hope this helped!

Answer:

3.15 N towards the positive x-axis

Explanation:

first charge has charge q1 = 10 μC = 10 x 10^-6 C

second charge has charge q2 = 20 μC = 20 x 10^-6 C

third charge has charge q3 = -30 μC = -30 x 20^-6 C

According to coulomb's law, force between two charged particle is given as

F = [tex]\frac{-kQq}{r^2}[/tex]

Where

F is the force between the charges

k is Coulomb's constant = 9 x 10^9 kg⋅m^3⋅s^−2⋅C^−2.

Q is the magnitude of one charge

q is the magnitude of the other charge

is the distance between these two charges

For the force on q2 due to q1,

distance r between them = 0 - (-1.0) = 1 m

F = [tex]\frac{-9*10^{9}*10*10^{-6}*20*10^{-6}}{1^2}[/tex] = -1.8 N (the negative sign indicates a repulsion on q2 towards the positive  x-axis)

For the force on q2 due to q3,

distance between them = 2.0 - 0 = 2 m

F = [tex]\frac{-9*10^{9}*20*10^{-6}*(-30*10^{-6})}{2^2}[/tex] = 1.35 N (the positive sign indicates an attraction on q2 towards the positive x-axis)

Resultant force on q2 = 1.8 N + 1.35 N = 3.15 N towards the positive x-axis

Answer:

false

Explanation:

burning something is a chemical change

Answer:

t the apparent weight of the body decreases when it is submerged in water,

 F'_{e} = mg - ρ_liquid g V

Explanation:

When a container is placed on a scale it falls due to the weight of the body and the needle attached to the spring shows the value of the weight that is proportional to the displacement of the spring.

When the body is immersed in a container with water, it exerts a push on the body, so its apparent weight decreases and the compression of the scale is less, therefore it indicates a smaller weight of the body.

Let's write the equilibrium equation for the body is placed on the scale without water

               [tex]F_{e}[/tex] - W = 0

               F_{e} = W

Let us propose the equilibrium equation for this case

            F'_{e} + B - W = 0

where F'_{e} is the elastic force, B the push of the liquid and W the weight of the body

            F'_{e} = W -B

The thrust of the liquid is given by the Archimedean principle which says that it is equal to the weight of the dislodged liquid

            B = ρ g V

             F'_{e} = mg - ρ_liquid g V      (1)

we use the density concept

            ρ_body = m / V

we substitute

             F'_{e}= g V (ρ_body - ρ_agua)          (2)

             F'_{e} < F_{e}

We see  from expression is 1 and 2 that the apparent weight of the body decreases when it is submerged in water,

To know the specific value of the decrease, the weight of the body in the air or its density and volume must be known

Answer:

Beat frequency together = 2.95 Hz (Approx)

Explanation:

Given:

Frequency (F) = 294 H

Decrease in tension = 2%

Find:

Beat frequency together

Computation:

Tension = (100 - 2) / 100

Tension (T) = 0.98

Beat frequency together = Frequency (F) - (√T × F)

Beat frequency together = 294 - (√0.98 × 294)

Beat frequency together = 2.95 Hz (Approx)

The beat frequency heard when the two strings are played together is 2.95 Hz.

Given data:

The tuning frequency of the violin is, f = 294 Hz.

Decrement in the tension is, 2 %.

Since, tension is reduced at the rate of 2%. Then the new magnitude of tension on the string is,

T = (100 - 2 )/100

T = 0.98

Then the expression for the beat frequency heard when the two strings are played together is given as,

[tex]f_{b}=f -(\sqrt{T \times f})[/tex]

Solving as,

[tex]f_{b}=294-(\sqrt{0.98 \times 294})\\\\f_{b}=2.95\;\rm Hz[/tex]

Thus, we can conclude that the beat frequency heard when the two strings are played together is 2.95 Hz.

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Answer:

Explanation:

height of the building h = 15 m

initial vertical velocity u = 0

v² = u² + 2 g h

u = 0 , final velocity after falling height h

h = 15

v² = 2 x 9.8 x 15

v = 17.14 m /s

. Time of fall be t

h = 1/2 g t²

15 = 1/2 x 9.8 x t²

t = 1.749 s

This time will be required for truck to come under the building .

speed = distance / time

distance = speed x time

= 22 x 1.749

38.5 m

Truck should be at a distance of 38.5 m . when the stuntman starts falling .

Part A: The time required to hit the truck by a stuntman is 1.749 s.

Part B: The distance between the building and truck is 38.47 m.

Given that the height h of the building is 15 m. The constant speed s of driving the truck is 22 m/s.

Part A

The final velocity can be calculated by the formula given below.

[tex]v^2 = u^2 + 2gh[/tex]

Where v is the final velocity, u is the initial velocity, g is the gravitational acceleration and h is the height of the building.

The initial velocity u will be zero and g = 9.8 m/s2.

Substituting the values,

[tex]v^2 = 0 + 2\times 9.8\times 15[/tex]

[tex]v^2 = 294[/tex]

[tex]v = 17.14 \;\rm m/s[/tex]

The time to hit the truck can be calculated as given below.

[tex]h = ut + \dfrac {1}{2}gt^2[/tex]

[tex]15 = 0 + \dfrac {1}{2}\times 9.8 \times t^2[/tex]

[tex]t^2 = 3.06[/tex]

[tex]t = 1.749 \;\rm s[/tex]

Hence we can conclude that the time required to hit the truck by stuntman is 1.749 s.

Part B

The distance between the building and truck is calculated as given below.

[tex]d = s \times t[/tex]

[tex]d = 22 \times 1.749[/tex]

[tex]d =38.47\;\rm m[/tex]

Hence the distance between the building and truck is 38.47 m.

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Answer:

Frequency of light = 5454.5 GHz

Refractive index = 1.46

speed of light in quartz = 2.05 x 10^8 m/s

Explanation:

The wavelength of the light λ = 550 nm = 550 x 10^-9 m

frequency = ?

Frequency of light f = c/λ

where

c is the speed of light = 3 x 10^8 m/s

substituting, we have

f = (3 x 10^8)/(550 x 10^-9)

frequency f = 5.4545 x 10^14 Hz

==> 5454.5 GHz

The relationship between refractive index is given as

n1 sinθ1 = n2 sinθ2

where

n1 is the refractive index of air = 1

θ1 is the angle of incidence = (90 -70) = 20°

θ2 is the angle of refraction = (90 - 76.46) = 13.54°

n2 is the refractive index of quartz

substituting values, we have

1 x sin 20 = n2 x sin 13.54

0.3420 = n2 x 0.2341

refractive index of quartz n2 = 0.3420/0.2341 = 1.46

From n = c/v

where

n is the refractive index of quartz

c is the speed of light in air = 3 x 10^8 m/s

v is the speed of light in quartz = ?

substituting values, we have

1.46 = (3 x 10^8)/v

v = (3 x 10^8)/1.46 = 2.05 x 10^8 m/s