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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?

Physics

2 answers:

Alina [70]3 years ago

7 0

A. is the right answer since work is negative and Q which is heat in negative also

Blizzard [7]3 years ago

3 0

Answer: Option A

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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The following table lists the work functions of a few commonmetals, measured in electron volts.

steposvetlana [31]

Answer:

Lithium

Explanation:

The equation for the photoelectric effect is

$\frac{hc}{\lambda}= \phi + K_{max}$

where

$\frac{hc}{\lambda}$ is the energy of the incident photon, with

h being the Planck constant

c is the speed of light

$\lambda$ is the wavelength of the photon

$\phi$ is the work function of the metal (the minimum energy needed to extract the photoelectron from the metal)

$K_{max}$ is the maximum kinetic energy of the emitted photoelectrons

In this problem, we have

$\lambda= 190 nm = 1.9\cdot 10^{-7}m$ is the wavelength of the incident photon

$K_{max}=4.0 eV$ is the maximum kinetic energy of the electrons

First of all we can find the energy of the incident photon

$E=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{1.90\cdot 10^{-7} m}=1.05\cdot 10^{-18} J$

Converting into electronvolts,

$E=\frac{1.05\cdot 10^{-18} J}{1.6\cdot 10^{-19} J/eV}=6.6 eV$

So now we can re-arrange the equation of the photoelectric effect to find the work function of the metal

$\phi = E-K_{max}=6.6 eV - 4.0 eV=2.6 eV$

So the metal is most likely Lithium, which has a work function of 2.5 eV.

3 0

3 years ago

Hannah has information about an object in circular orbit around Earth.

Elena-2011 [213]

The correct answer is:

the distance of the orbiting object to Earth.

In fact, we know that the gravitational force that keeps the object in circular motion around the Earth is equal to the centripetal force, so we can write:

$G\frac{Mm}{r^2}=m\frac{v^2}{r}$

If we re-arrange the equation, we find an expression for the tangential speed of the object:

$v=\sqrt{\frac{GM}{r}}$

and we see that it depends on 3 quantities: G, M (the mass of the Earth) and r (the distance of the object from the Earth).

3 0

3 years ago

Read 2 more answers

If an earthquake occurred in Miami, Florida, then how long would it take for a seismic station in Seattle, Washington, to pick u

Juliette [100K]

0.017s

Explanation:

Given parameter

Distance = 5000km = 5 x 10⁶m

Unknown:

time taken = ?

Solution:

We use the normal speed equation to solve this problem as we take the speed of the wave to be 3 x 10⁸m/s.

Speed = $\frac{Distance }{Time taken}$

Inputting the parameters:

Time taken = $\frac{distance }{velocity of the wave}$

Time taken = $\frac{ 5 000000}{3 00000000}$ = 0.017s

Learn more:

Earthquake brainly.com/question/11292835

#learnwithBrainly

8 0

3 years ago

Two tugboats pull a disabled supertanker. Each tug exerts a constant force of 1.8×106N , one an angle 11degrees west of north an

sp2606 [1]

Answer: 2,9 ×10¹⁰J.

Explanation:

1. The work is a measure of energy and is calculated as the product of the displacement times the parallel force to such displacement.

That means that the only components of the force that contribute to work are those that result parallel to the displacement.

2. Since it is given that the two tugboats "pull the tanker a distance 0.83km toward the north", that is the displacement, and you have to calculate the net force toward the north.

3. Tugboat #1.

a) Force magnitude: F₁ = 1.8×10⁶N

b) Angle: α = 11° West of North

c) North component of the force F₁: Fy₁ = F₁cos(α) = 1.8×10⁶N × cos(11°) = 1.77×10⁶N

4. Tugboat #2:

a) Force magnitude: F₂ = 1.8×10⁶N

b) Angle: = 11° East of North

c) North component of the force F₂: Fy₂ = F₂cos(β) = 1.8×10⁶N × cos(11°) = 1.77×10⁶N =

5. Total net force, Fn:

Fn = Fy₁ + Fy₂ = 1.77×10⁶N + 1.77×10⁶N = 3.54×10⁶N

6. Work, W:

Displacement, d = 0.83 km = 8,300 m

W = Fn×d = 3.54×10⁶N×8,300m = 29,000 ×10⁶J = 2,9 ×10¹⁰J

The answer is rounded to two significant figures because both data, Force and displacement, have two significant figures.

7 0

3 years ago

- A fridge has a maximum static friction force

Dennis_Churaev [7]

Answer:

They will move the fridge if they all push in the same direction, but it will not move with constant velocity

Explanation:

The maximum static friction force is

$F_f = -250 N$ (negative sign since its direction is opposite to the push applied by the people)

Sam can apply a force of 130 N, while Amir and Andre can apply a push of 65 N each, so the total force that they can apply, if they push in the same direction, will be:

$F=130 + 65 +65=260 N$

This force is larger than the frictional force, so the fridge will start moving.

However, the net force on the fridge will be:

$\sum F = 260 N - 250 N = 10 N$

And according to Newton's second law,

$\sum F = ma$

where m is the mass of the fridge and a its acceleration, since the net force is not zero, then the fridge will have a non-zero acceleration, so it will not move with constant velocity.

3 0

3 years ago