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4 years ago

Describe how we can use scientific knowledge and reasoning to help guide us when making decisions

1 answer:

7 0

<span>A very simple example is the light bulb question. If the light bulb in your room goes out, scientific reasoning will first attribute it to a short circuit. Then, after setting up the hypothesis, we go and check if changing the fuse solves the problem. if not, the hypothesis is rejected and we change the hypothesis and do another experiment.</span>

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Joanna's house is 8000 feet due west of her school. If her house is assigned the position of zero and her school is assigned the

olchik [2.2K]

Answer:

Joanna's position would be -100.

Explanation:

Joanna's position would be 100 feets west to her house. Her position is negative because Joanna walked west of her house. The position would have been positive if she had moved east of his house, that is, to the school.

8 0

3 years ago

If a wave has a frequency of 2 HZ what would it be in seconds?

gavmur [86]

Frequency is not a length of time. It's exactly the opposite.
Frequency tells you how often something happens. In fact,
the unit 'Hz' means 'per second'.

Frequency of 2 Hz means "It happens at 2 per second."

The time it takes for the thing to happen once is exactly the
'reciprocal' of the frequency ... ' 1 ' divided by the frequency.

If the frequency is 2 Hz, then the thing happens every 1/2 second.

If the frequency is 74 Hz, then it happens every 1/74 of a second.

If the frequency is 1 KiloHz, then it happens every 1/1000 second.

8 0

4 years ago

A boulder is raised above the ground, so that its potential energy relative to the ground is 200 J. Then it is dropped. Estimate

babymother [125]

Answer:

200 J

Explanation:

In this problem, I assume there is no air resistance, so the system is isolated (=no external forces).

For an isolated system, the total mechanical energy is constant, and it is given by:

$E=KE+PE$

where

KE is the kinetic energy

PE is the potential energy

The kinetic energy is the energy due to the motion of the object, while the potential energy is the energy due to the position of the object relative to the ground.

At the beginning, when the boulder is raised above the ground, its height above the ground is maximum, while its speed is zero; it means that all its mechanical energy is just potential energy, and it is:

$E=PE_{max}=200 J$

As the boulder falls down, its altitude decreases, so its potential energy decreases, while the speed increases, and the kinetic energy increases. Therefore, potential energy is converted into kinetic energy.

Eventually, just before the boulder hits the ground, the height of the object is zero, and the speed is maximum; this means that all the energy has now converted into kinetic energy, and we have

$E=KE_{max}=200 J$

Therefore, the kinetic energy just before hitting the ground is 200 J.

6 0

3 years ago

Elsa has three metal blocks that look the same.

9966 [12]

Answer:

Aluminium is lightweight

Iron is magnetic

and one is not magnetic

4 0

3 years ago

Suppose Gabor, a scuba diver, is at a depth of 15m. Assume that: The air pressure in his air tract is the same as the net water

s2008m [1.1K]

Complete Question

The complete question is shown on the first and second uploaded image

Answer:

Now the ratio of the gases in Gabor's lungs at the depth of 15m to that at

the surface is $\frac{(n/V)_{15\ m}}{(n/V)_{surface}} = 2.5$

The number of moles of gas that must be released is $n= 0.3538\ mols$

Explanation:

We are told from the question that the pressure at the surface is 1 atm and for each depth of 10m below the surface the pressure increase by 1 atm

This means that the pressure at the depth of the surface would be

$P_d = [\frac{15m}{10m} ] (1 atm) + 1 atm$

$= 2.5 atm$

The ideal gas equation is mathematically represented as

$PV = nRT$

Where P is pressure at the surface

V is the volume

R is the gas constant = 8.314 J/mol. K

making n the subject we have

$n = \frac{PV}{RT}$

Considering at the surface of the water the number of moles at the surface would be

$n_s = \frac{P_sV}{RT}$

Substituting $1 atm = 101325 N/m^2$ for $P_s$ , $6L = 6*10^{-3}m^3$ for volume , 8.314 J/mol. K for R , (37° +273) K for T into the equation

$n_s = \frac{(1atm)(6*10^{-3} m^3)}{(8.314J/mol \cdot K)(37 +273)K}$

$= 0.2359 mol$

To obtain the number of moles at the depth of the water we use

$n_d = \frac{P_d V}{RT}$

Where $P_d \ and \ n_d \$ are pressure and no of moles at the depth of the water

Substituting values we have

$n_d = \frac{(2.5)(101325 N/m^2)(6*10^{-3}m^3)}{(8.314 J/mol \cdot K)(37 + 273)K}$

$= 0.5897 mol$

Now to obtain the number of moles released we have

$n = n_d - n_s$

$= 0.5897mol - 0.2359mol$

$=0.3538 \ mol$

The molar concentration at the surface of water is

$[\frac{n}{V} ]_{surface} = \frac{0.2359mol}{6*10^-3m^3}$

$=39.31mol/m^3$

The molar concentration at the depth of water is

$[\frac{n}{V} ]_{15m} = \frac{0.5897}{6*10^{-3}}$

$= 98.28 mol/m^3$

Now the ratio of the gases in Gabor's lungs at the depth of 15m to that at the surface is

$\frac{(n/V)_{15\ m}}{(n/V)_{surface}} = \frac{98.28}{39.31} =2.5$

6 0

3 years ago