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Ksenya-84 [330]
3 years ago
8

A department store expects to have 225 customers and 20 employees at peak times in summer. Determine the contribution of people

to the total cooling load of the store. The average rate of heat generation from people doing light work is 115 W, and 70% of it is in sensible form.
Physics
1 answer:
stiks02 [169]3 years ago
3 0

Answer:

<em>The  contribution of people to the cooling load of the store is 19722.5 W</em>

Explanation:

Total amount of customers = 225

Total amount of employees = 20

Total amount of people in the store at that instant n = 245 people

Average rate of heat generation Q = 115 W

percentage of these heat generated that is sensible heat = 70%

Sensible heat raises the surrounding temperature. Latent heat only causes a change of state.

The total heat generated by all the people in the store = n x Q

==> 245 x 115 = 28175 W

but only 70% of this heat is sensible heat that raises the temperature of the store, therefore, the contribution of people to the cooling load of the store = 70% of 28175 W

==> 0.7 x 28175 = <em>19722.5 W</em>

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A small car with mass of 0.800 kg travels at a constant speed
Alexandra [31]

Answer:

The equation of equilibrium at the top of the vertical circle is:

\Sigma F = - N - m\cdot g = - m \cdot \frac{v^{2}}{R}

The speed experimented by the car is:

\frac{N}{m}+g=\frac{v^{2}}{R}

v = \sqrt{R\cdot (\frac{N}{m}+g) }

v = \sqrt{(5\,m)\cdot (\frac{6\,N}{0.8\,kg} +9.807\,\frac{kg}{m^{2}} )}

v\approx 9.302\,\frac{m}{s}

The equation of equilibrium at the bottom of the vertical circle is:

\Sigma F = N - m\cdot g = m \cdot \frac{v^{2}}{R}

The normal force on the car when it is at the bottom of the track is:

N=m\cdot (\frac{v^{2}}{R}+g )

N = (0.8\,kg)\cdot \left(\frac{(9.302\,\frac{m}{s} )^{2}}{5\,m}+ 9.807\,\frac{m}{s^{2}} \right)

N=21.690\,N

7 0
3 years ago
Q4. A particle starting from rest, travels with a = 5 m/s2. What is the distance traveled in 10 sec?
anzhelika [568]

Answer:

250 m

Explanation:

Given :

Initial velocity, u = 0

Acceleration, a = 5 m/s2

Time elapsed is t = 10 seconds

The distance traveled in 10 seconds by the particle when accelerating at 5 m/s2 is given by,

$ x = ut+\frac{1}{2}at^2$

Putting the values,

$ x = 0\times 10+\frac{1}{2}(5)(10)^2$

$ x =\frac{1}{2}(5)(100)$

x = 250 m

The particle moved 250 m in 10 seconds

3 0
3 years ago
Automobile air bags use the decomposition of sodium azide as their sources of gas for rapid inflation, represented in the reacti
NeTakaya

Answer : The mass of NaN_3 required is 71.175 grams.

Explanation :

To calculate the moles of nitrogen gas, we use the equation given by ideal gas :

PV = nRT

where,

P = Pressure of nitrogen gas = 763 torr

V = Volume of the nitrogen gas = 40.0 L

n = number of moles of gas = ?

R = Gas constant = 62.364\text{ L.torr }mol^{-1}K^{-1}

T = Temperature of helium gas = 25^oC=273+25=298K

Putting values in above equation, we get:

763torr\times 40.0L=n\times 62.364\text{ L.torr }mol^{-1}K^{-1}\times 298K\\\\n=1.642mol

Now we have to calculate the moles of NaN_3.

The balanced chemical reaction is:

2NaN_3(s)\rightarrow 2Na(s)+3N_2(g)

From the balanced chemical reaction, we conclude that

As, 3 moles of N_2 produced from 2 moles NaN_3

So, 1.642 moles of N_2 produced from \frac{2}{3}\times 1.642=1.095 moles NaN_3

Now we have to calculate the mass of NaN_3.

Molar mass of NaN_3 = 65 g/mol

\text{Mass of }NaN_3=\text{Moles of }NaN_3\times \text{Molar mass of }NaN_3

\text{Mass of }NaN_3=1.095mole\times 65g/mole=71.175g

Therefore, the mass of NaN_3 required is 71.175 grams.

5 0
4 years ago
how do humans judge temperature without the use of instruments such as thermometers? choose the most common process.
Schach [20]

Some humans judge temperature without the use of instruments include:

  • touching the object
  • feeling the radiant energy

<h3>What is temperature?</h3>

Temperature is the measure of the degree of hotness or coldness of a substance.

Temperature of substances are usually measured using thermometers.

The choice of thermometer depends on the temperature range to be measured.

However, some crude ways of measuring temperature include:

  • touching the object
  • feeling the radiant energy

In conclusion, temperature measures the hotness or coldness of objects.

Lear more about temperature at: brainly.com/question/25677592

#SPJ1

5 0
2 years ago
You have a mass of 55kg and are riding your frictionless skateboard, which has a mass of 5kg, in a straight line at a speed of 4
Rzqust [24]

Given

m1(mass of the first object): 55 Kg

m2 (mass of the second object): 55 Kg

v1 (velocity of the first object): 4.5 m/s

v2 (velocity of the second object): ?

m3(mass of the object dropped): 2.5 Kg

The law of conservation of momentum states that when two bodies collide with each other, the momentum of the two bodies before the collision is equal to the momentum after the collision. This can be mathemetaically represented as below:

Pa= Pb

Where Pa is the momentum before collision and Pb is the momentum after collision.

Now applying this law for the above problem we get

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Momentum after collision = (m1+m2+m3) x v2 =(55+5+2.5) x v2

Now we know that Momentum before collision= momentum after collision.

Hence we get

270 = 62.5 v2

v2 = 4.32 m/s




7 0
3 years ago
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