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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. <span>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.</span>

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 plane accelerates from rest at a constant rate of 5.00 m/s2 along a runway that is 1800 m long. Assume that the plane reaches

tiny-mole [99]

Answer:

26.8 seconds

Explanation:

To solve this problem we have to use 2 kinematics equations: *I can't use subscripts for some reason on here so I am going to use these variables:

v = final velocity

z = initial velocity

x = distance

t = time

a = acceleration

${v}^{2} = {z}^{2} + 2ax$

$v = z + at$

First let's find the final velocity the plane will have at the end of the runway using the first equation:

${v}^{2} = {0}^{2} + 2(5)(1800)$

$v = 60 \sqrt{5}$

Now we can plug this into the second equation to find t:

$60 \sqrt{5} = 0 + 5t$

$t = 12 \sqrt{5}$

Then using 3 significant figures we round to 26.8 seconds

3 0

3 years ago

(11) The speed of radio waves is 300 000 000 m/s.

Neko [114]

Answer:

Wavelength = 9.68 meters

Explanation:

Given the following data;

Speed = 300,000,000m/s

Frequency = 31 Megahertz to Hertz = 31 * 10⁶ Hz

To find the wavelength;

Wavelength = speed/frequency

Wavelength = 300,000,000/31,000,000

Wavelength = 9.68 meters

7 0

3 years ago

An orbiting satellite can become charged by the photoelectric effect when sunlight ejects electrons from its outer surface. Sate

Rufina [12.5K]

Answer:

the longest wavelength of incident sunlight that can eject an electron from the platinum is 233 nm

Explanation:

Given data

Φ = 5.32 eV

to find out

the longest wavelength

solution

we know that

hf = k(maximum) +Ф ...............1

here we consider k(maximum ) will be zero because photon wavelength max when low photon energy

so hf = 0

and hc/ λ = +Ф

so λ = hc/Ф ................2

now put value hc = 1240 ev nm and Φ = 5.32 eV

so hc = 1240 / 5.32

hc = 233 nm

the longest wavelength of incident sunlight that can eject an electron from the platinum is 233 nm

8 0

3 years ago

Case 1: A 0.780-kg silver pellet with a temperature of 85 oC is added to 0.150 kg of water in a copper cup of unknown mass. The

suter [353]

Answer: The silver pellet will release heat

Explanation:

Based on the case scenario, the silver pellet has a higher temperature that the system of water and copper cup and is thereby added to the system. Because of the higher kinetic energy of the molecules of silver in the silver pellet, some of energy will be released to the water and copper cup system because the system will aim to achieve thermal equilibrium.

4 0

3 years ago

7th Grade

slamgirl [31]

A is the correct answer: 100 degrees C is the boiling point of water, just subtract 82 from 100.

3 0

2 years ago