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3 years ago

Which of the following situations would cause the greatest decrease in the motion of molecules in a system?

2 answers:

6 0

The answer is A. Q = -50 J, W = -50 J. A decrease in the motion of molecules in a system can be interpreted as a decrease or release in energy which means that energy should be negative. For the formula of energy:

U = Q + W

U is negative for the case of A. This gives the greatest decrease in the molecules' motion.

astra-53 [7]3 years ago

6 0

Answer:

Explanation:

Now, i will consider that W and A refers to the work and heat done/applied to the system

Always Q is related to the heat, so if Q is positive this means that the temperature of the system increase if Q is negative this means that heat is extracted from the system, and the temperature decreases, which implies that the motion of the particles decreases.

For the work is the same, if the applied work is positive, then the energy of the system increments (suppose a gas inside a piston, if you compress the piston the work is positive, and now the particles are close together, wich increments the temperature of the gas)

If the work is negative, this means that the system does the work, so the energy decreases, and also the motion of the particles, so the correct option A

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A person in bare feet is standing under a tree during a thunderstorm, seeking shelter from the rain. A lightning strike hits the

Anni [7]

Answer:

$I=38.181\ A$ is the current through the body of the man.

$E=34.5\ J$ energy dissipated.

Explanation:

Given:

time for which the current lasted, $t=43\times 10^{-6}\ s$

potential difference between the feet, $V=21000\ V$

resistance between the feet, $R=550\ \Omega$

Now, from the Ohm's law we have:

$I=\frac{V}{R}$

$I=\frac{21000}{550}$

$I=38.181\ A$ is the current through the body of the man.

Energy dissipated in the body:

$E=I^2.R.t$

$E=38.181^2\times 550\times 43\times 10^{-6}$

$E=34.5\ J$

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3 years ago

The ratio of the focal length of a lens to it's diameter is the

user100 [1]

Answer:

The f-ratio describes the relationship between the lens diameter and the focal length and is calculated by dividing the focal length by the diameter of the lens. For example, if a lens were to have a focal length of 50mm and a diameter of 10mm, then the f-ratio would be 50mm/10mm=5 or otherwise referred to as f5.

Explanation:

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3 years ago

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Who’s of the following is classified as a salt: ammonia or sodium chloride?

Temka [501]

Sodium Chloride could be classified as a salt.

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3 years ago

Is the strange solid/liquid changing behavior of Oobleck the SAME as an ice cube melting?

Dmitrij [34]

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3 years ago

Steam is leaving a pressure cooker whose operating pressure is 20 psia. It is observed that the amount of liquid in the cooker h

Debora [2.8K]

Answer:

a) 34.05ft/s

b).1156.2BTU/lbm

c) 2.04BTU/s

Explanation:

Amount of liquid that has evaporated, m = ◇Vliq/ Vf

We replace the values to make conversion

m = (0.6gal/ 0.01683ft^3/lbm) × (0.13368ft^3/1gal)

m = 4.755lb

The mass flow rate of exit steam is given by:

m' = m/◇t

We replace values to make conversion

m' =( 4.766lb/45min) = 0.1059lb/min × 1min/60s

m' = 0.001765lb/s

The exit velocity V = m'/pA = m'Vg/A

We replace values to make conversion

V =[ (0.001765lbm/s)(20.093ft^3/lbm) /(0.15 in^2)]× (144in^2/1ft^2)

V = 34.05ft/s

b) The total and flow energies per unit mass is given by:

Eflow= Pv = h - u

We replace the values to make conversion

Eflow = 1156.2 - 1081.8

Eflow = 74.4BTU/lbm

Therefore theta= h + ke + pe

Theta approximately =h = 1156.2BTU/lbs

c) The rate at which energy is leaving the cooler by steam is given by:

Emass = m'theta

Emass = (0.001765)×(1156.2)

Emass = 2.04BTU/s

6 0

3 years ago