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3 years ago

For an object that’s in static equilibrium which of the following statements must be true? Check all that apply.

2 answers:

5 0

The statements that are held true with regards to the static equilibrium of bodies are:

The net torque acting on the object must equal zero

The net torque on the object does not have to be zero if the net force on the object is zero

Furthermore, when a body is in a state of static equilibrium, the summation of all forces, either vertically or horizontally, must be equal to zero.

kow [346]3 years ago

5 0

The statements that are held true with regards to the static equilibrium of bodies are:
1. The net torque acting on the object must equal zero.

According to the first Condition of Equilibrium, an object to be in equilibrium, it must have zero acceleration. This means that both the net force and the net torque on the object must be zero and forces acting on it should add up to zero.

2. The net torque on the object does not have to be zero if the net force on the object is zero.

According to the first condition equilibrium, the net force on the object must be zero for the object to be in equilibrium. If net force is zero, the net force along any direction is also zero.

Furthermore, when a body is in a state of static equilibrium, the summation of all forces, either vertically or horizontally, must be equal to zero.

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Which of the following involve an increase in the entropy of the system under consideration? a. melting of a solid b. evaporatio

Mama L [17]

Explanation:

Since, entropy is the measure of degree of randomness. So, more randomly the molecules of a substance are moving more will be its entropy.

For example, when a solid melts then it means heat is absorbed by it due to which its molecules have gained energy. As a result, they collide with each other and hence, entropy will increase.

Evaporation of a liquid will also cause the liquid to change its state from liquid to gas. This means molecules will go far away from each other leading to an increase in the entropy.

Sublimation is a process of conversion of a solid into gaseous phase without going through liquid phase. So, in this case also entropy will increase due to gain in energy by the molecules of a solid.

In freezing, molecules of a substance come closer to each other and acquire less energy. Hence, entropy decreases.

Mixing is a process of combining two or more substances physically with each other. This leads to increase in entropy of a substance.

In separation molecules are separated from each other leading to a decrease in energy. Hence, entropy will also decrease.

Diffusion is a process in which molecules are able to rapidly move from one place to another. Hence, entropy increases when diffusion takes place.

Thus, we can conclude that melting of a solid, evaporation of a liquid, sublimation, mixing and diffusion involve an increase in the entropy of the system under consideration.

8 0

3 years ago

A light source of wavelength λ illuminates a metal with a work function (a.k.a., binding energy) of BE=2.00 eV and ejects electr

slega [8]

<h2>Answer: 1.011 eV</h2>

Explanation:

The described situation is the photoelectric effect, which consists of the emission of electrons (electric current) that occurs when light falls on a metal surface under certain conditions.

If we consider the light as a stream of photons and each of them has energy, this energy is able to pull an electron out of the crystalline lattice of the metal and communicate, in addition, a kinetic energy.

This is what Einstein proposed:

Light behaves like a stream of particles called photons with an energy $E$ :

$E=h.f$ (1)

So, the energy $E$ of the incident photon must be equal to the sum of the Work function $\Phi$ of the metal and the kinetic energy $K$ of the photoelectron:

$E=\Phi+K$ (2)

Where $\Phi$ is the minimum amount of energy required to induce the photoemission of electrons from the surface of a metal, and its value depends on the metal. 

In this case $\Phi=2eV$ and $K_{1}=4eV$

So, for the first light source of wavelength $\lambda_{1}$ , and applying equation (2) we have:

$E_{1}=2eV+4eV$ (3)

$E_{1}=6eV$ (4)

Now, substituting (1) in (4):

$h.f=6eV$ (5)

Where:

$h=4.136(10)^{-15}eV.s$ is the Planck constant

$f$ is the frequency

Now, the frequency has an inverse relation with the wavelength

$\lambda_{1}$ :

$f=\frac{c}{\lambda_{1}}$ (6)

Where $c=3(10)^{8}m/s$ is the speed of light in vacuum

Substituting (6) in (5):

$\frac{hc}{\lambda_{1}}=6eV$ (7)

Then finding $\lambda_{1}$ :

$\lambda_{1}=\frac{hc}{6eV }$ (8)

$\lambda_{1}=\frac{(4.136(10)^{-15} eV.s)(3(10)^{8}m/s)}{6eV}$

We obtain the wavelength of the first light suorce $\lambda_{1}$ :

$\lambda_{1}=2.06(10)^{-7}m$ (9)

Now, we are told the second light source $\lambda_{2}$ has the double the wavelength of the first:

$\lambda_{2}=2\lambda_{1}=(2)(2.06(10)^{-7}m)$ (10)

Then: $\lambda_{2}=4.12(10)^{-7}m$ (11)

Knowing this value we can find $E_{2}$ :

$E_{2}=\frac{hc}{\lambda_{2}}$ (12)

$E_{2}=\frac{(4.136(10)^{-15} eV.s)(3(10)^{8}m/s)}{4.12(10)^{-7}m}$ (12)

$E_{2}=3.011eV$ (13)

Knowing the value of $E_{2}$ and $\lambda_{2}$ , and knowing we are working with the same work function, we can finally find the maximum kinetic energy $K_{2}$ for this wavelength:

$E_{2}=\Phi+K_{2}$ (14)

$K_{2}=E_{2}-\Phi$ (15)

$K_{2}=3.011eV-2eV$

$K_{2}=1.011 eV$ This is the maximum kinetic energy for the second light source

7 0

3 years ago

Does a cool pond have more or less heat energy than a red-hot iron nail? Explain

eimsori [14]

Answer:

Less heat energy

Explanation:

cus I said so

8 0

3 years ago

Read 2 more answers

I NEED HELP PLZ. can some one explain partial variation

dezoksy [38]

Answer:

Explanation:

Partial Variation is a relation that is of the form y = mx+b. The graph of y = mx+b is a straight line with the slope of m and a y-intercept of b. ... The relation y = mx +b represents partial variation because the value of y varies partially with the value of x.

8 0

2 years ago

1.Wave motion that is parallel to the wave direction is described

Dafna1 [17]

Answer:

Explanation:

A wave is a phenomenon that travels through a material medium without any permanent effect on the medium. It can be classified as mechanical or electromagnetic waves. And the two major types are transverse and longitudinal.

From the given question;

1. Longitudinal waves e.g sound waves, waves in a spring'

2. Frequency (number of cycles per second).

3. Wavelength of the wave. Measured in meters.

4. Transverse waves e.g light waves, water waves.

5. Wave speed.

6. Electromagnetic waves e.g ultraviolet waves, X-rays etc.

7. Amplitude.

8. Hertz.

9. Rarefaction

10. Compression

7 0

2 years ago