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bogdanovich [222]
3 years ago
14

Why is it important to use placebos and a double-blind approach in some studies

Physics
1 answer:
viktelen [127]3 years ago
6 0
Another name for these two words is "constant" and you want to have a "constant", because you want something to compare your experimental group to, to see whether data had changed or not. So you have placebos or a double- blind to compare your experimental group to it and also so you know you don't have a bias or anything in the study.
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What happens when a sound wave passes from oil into air? A. the sound wave slows down and bounces back B. the sound wave slows d
Jlenok [28]

Oil is optically denser than water. When sound/light goes from optically denser medium to optically rarer medium, their velocity increase and they moves away for normal.

<h3><u>Appropriate</u><u> </u><u>Answer</u><u>:</u></h3>

The sound wave speeds up and bends

\Large{ \underline{ \boxed{ \pink{ \bf{Option \: (D)}}}}}

As, In optics we learnt that light undergoes refraction when travels from medium of different densities. Similarly, Sound also follows the law of refraction.

  • It is due to the change of speed of water in different mediums, This makes it speed up or down depending upon the medium and their densities.

<u>━━━━━━━━━━━━━━━━━━━━</u>

6 0
3 years ago
Which two processes increase the motion of the molecules?
anzhelika [568]
The answer is 2 because a and b are slowing it down by condensing it and then freezing it so its not one, b and c are opposites because b slows it down whereas c speeds it up so its not 3, and number 4 is the same explanation for number 3
hope you pass :)
5 0
3 years ago
A puck of mass 0.5100.510kg is attached to the end of a cord 0.8270.827m long. The puck moves in a horizontal circle without fri
yanalaym [24]

Answer: 2.75 1/sec

Explanation:

The only external force (neglecting gravity) acting on the puck, is the centripetal force, which. in this case, is represented by the tension in the string, so we can say:

T = mv² / r (1)

Our unknown, is the frequency at which the puck can go around the circle, which is the inverse of the period Tp.

By definition, a period is the time needed by the puck to complete one entire circle.

By definition also , angular velocity is the rate of change of the angle advanced, so we can express this way:

ω = ∆θ / ∆t  

The angle advanced during one period, is exactly (by angle definition) 2 π radians.

So, we can always write the angular velocity, ω, as follows:

ω = 2π / Tp = 2πf

Now, there is a relationship between linear and angular velocity, that can be found applying simply the definition of velocity and of an angle too, as follows:

v = ∆s / ∆t = r ∆θ/∆t = ω r

Replacing in (1), we have:

T = mω2 r2 / r = m ω2r (2)

We have just found that ω= 2πf, so, replacing in (2) :

T = m (2π)2 f2 r  

Solving for f:

f = 1/2π√(T/mr) = 1/2π 17.28 1/sec = 2.75 1/sec

6 0
3 years ago
I'd like you to explain this to me, I don't have a clue on how to do this
Westkost [7]

Answer:

Explanation:

The Spanish flu pandemic of 1918, the deadliest in history, infected an estimated 500 million people worldwide about one-third of the planet’s population and killed an estimated 20 million to 50 million victims, including some 675,000 Americans. The 1918 flu was first observed in Europe, the United States and parts of Asia before swiftly spreading around the world. At the time, there were no effective drugs or vaccines to treat this killer flu strain. Citizens were ordered to wear masks, schools, theaters and businesses were shuttered and bodies piled up in makeshift morgues.

Does this sound familiar?

Its the same thing but with a different name called the Corona virus pandemic the same thing happened in 1918 and now it is happening again in 2020 , but in in 2020 there are far less people infected by the Corona virus as compared to the Spanish flu the numbers approximate around 70 million infected and deaths are around 2 million.

The rapid spread of Spanish flu in the fall of 1918 was at least partially to blame on public health officials unwilling to impose quarantines during wartime. The public health response to the crisis in the United States was further hampered by a severe nursing shortage as thousands of nurses had been deployed to military camps and the front lines. But one of the chief reasons that the Spanish flu claimed so many lives in 1918 was that science simply didn’t have the tools to develop a vaccine for the virus. Microscopes couldn’t even see something as incredibly small as a virus until the 1930s.

That is why the Spanish Flu claimed so many lives in 1918 and the Corona Virus didn't claim that many.

The Corona Virus patients with respect to Spanish Flu patients exponentially decreased because in 2020 we had the specific tools to fight the virus and since mankind was aware when the world engrossed into the pandemic 100 years before the new the risks that it could impose on the world , People started to Quarantine themselves, more nurses/doctors are available rather than in the era of the 19th century.

Mathematically we would say that the exponential growth would be:

y=ab^x

This is an exponential function, which means as you increase  x , y  increases exponentially, and where a is the initial value and b is the growth factor.

For example:

There are 100,000 cases of Coronavirus when the virus outbroke. If the number of cases doubles every week then how many cases would be there in 10 weeks?

So the solution would be

y=ab^x\\y=100000(2)^{10}\\y=102400000

Which means people infected with the virus would be approximate 102.5 million. But since this kind of pandemic already broke out in 1918 called the Spanish flu mankind was wise and controlled its growth factor (b) by Quarantining people , shutting down businesses, schools  and implying them to work from home , closing off cafeteria's restaurants for dine in purposes and just allowing take away to reduce human contact, and since 1918 we have more doctors and nurses to treat the infected in 2020 we reduced the outbreak to 70 million in about 10 months other wise it could have been 100 million in just 2.5 months as we can see.

So guys stay indoors just go out if you REALLY need something, avoid meeting others , wear masks and gloves :)

4 0
3 years ago
Assume a solar cell would produce a current of 500mA and 3 V. What is the power of this solar cell?
defon

Answer:

the power of the solar cell is 1.5 watts

Explanation:

Recall that power is defined as the product of the voltage (V) times the running current (I): Power = V * I.

The only thing we have to take care of before actually performing the operation, is to convert milliamps into Amps, so our answer comes directly in the appropriate units (Watts). 500 mAmps can be written as 0.5 Amps, then, the product becomes:

Power = V * I = 3 V * 0.5 Amps = 1.5 watts

8 0
3 years ago
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