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3 years ago

What is scientific evidence and when do we have enough?

1 answer:

4 0

Scientific evidence is evidence that is backed up by science and you have enough when you can understandingly prove your point or hypothesis

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An electric hair dryer is rated 350w 110v. the safety fuse in the circuit can withstand 12a of current. how many hair dryers can

spayn [35]

To determine the number of hair dryers that can be plugged in to a circuit, our basis is the maximum threshold of the current. The current which measures 12 Amperes. This current already incorporates the safety factor that is important in industrial setting.

The voltage and the current can be related to the power by the equation:

P = I*V, where I is the current in Amperes and V is the voltage in volts

Solving for the total power:

P = 12 A * 110 V
P = 1,320 Watts

Since the power rating of each hair dryer is 350 W, we divide this to the total power to determine the capacity.

Number of hair dryers = 1,320 Watts/350 Watts per hair dryer
Number of hair dryers = 3.77

In this case, we cannot round off to 4 because this would already exceed the maximum power capacity. Therefore, the total number of hair dryers allowable is 3.

8 0

4 years ago

A container contains 26 ounces of salt. Convert 26 ounces to pounds.

Reika [66]

Answer:

1.625 Pounds Explanation:

5 0

3 years ago

Read 2 more answers

A block is at rest on the incline shown in the gure. The coefficients of static and kinetic friction are 0.6 and 0.51, respec- t

Alekssandra [29.7K]

Normal reaction force on the block while it is at rest on the inclined plane is given as

$F_n = mgcos\theta$

here we know that

m = 46 kg

$\theta = 29^o$

now we will have

$F_n = 46*9.8*cos29 = 394.3 N$

now the limiting friction or maximum value of static friction on the block will be given as

$F_s = \mu_s * F_n$

$F_s = 0.6 * 394.3 = 236.56 N$

Above value is the maximum value of force at which block will not slide

Now the weight of the block which is parallel to inclined plane is given as

$F_{||} = mg sin\theta$

here we know that

$F_{||} = 46*9.8 sin29 = 218.55 N$

Now since the weight of the block here is less than the value of limiting friction force and also the block is at rest then the frictional force on the block is static friction and it will just counter balance the weight of the block along the inclined plane.

So here <u>friction force on the given block will be same as its component on weight which is 218.55 N</u>

5 0

3 years ago

A thin oil slick (no=1.50) floats on water (nw=1.33). When a beam of white light strikes this film at normal incidence from air,

Sedbober [7]

Answer:

The (minimum) thickness of the oil slick is 325 nm.

Explanation:

Let the (minimum) thickness of the oil slick = $t_{o}$

Therefore:

2 $t_{o}$ = ( $m_{red}$ + $\frac{1}{2}$ )*λ $_{red}$ / $n_{o}$ (1)

similarly,

2 $t_{o}$ =( $m_{violet}+\frac{1}{2}$ )*λ $_{violet}$ / $n_{o}$ (2)

Thus, equation 1 = equation 2

( $m_{red}$ + $\frac{1}{2})$ *λ $_{red} /n_{o}$ = ( $m_{violet}+\frac{1}{2})$ *λ $_{violet}/n_{o}$

Where:

λ $_{red} = 650 nm$

λ $_{violet} = 390 nm$

$n_{o} = 1.5$

Therefore:

$\frac{2m_{violet}+1 }{2n_{red}+1 }$ =650/390=5/3

This shows that,

$m_{violet}$ =2

$m_{red}$ =1

Thus, using equation 2

$t_{o}$ = $\frac{5*390}{2*2*1.5} =325 nm$

6 0

3 years ago

The drinking water needs of an office are met by cooling tab water in a refrigerated water fountain from 23 to 6°C at an average

Ratling [72]

Answer:

The correct option is;

Explanation:

Here we have the Coefficient Of Performance, COP given by

$COP = \frac{Q_{cold}}{W} = 3.1$

The heat change from 23° to 6°C for a mass of 10 kg/h which is equivalent to 10/(60×60) kg/s or 2.78 g/s we have

$Q_{cold}$ = m·c·ΔT = 2.78 × 4.18 × (23 - 6) = 197.39 J

Therefore, plugging in the value for $Q_{cold}$ in the COP equation we get;

$COP = \frac{197.39 }{W} = 3.1$ which gives

$W = \frac{197.39 }{3.1} = 63.674 \ J$

Since we were working with mass flow rate then the power input is the same as the work done per second and the power input to the refrigerator = 63.674 J/s ≈ 64 W.

The power input to the refrigerator is approximately 64 W.

4 0

4 years ago

Read 2 more answers