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3 years ago

At a constant pressure, melting occurs by A) producing energy. B) absorbing energy. C) releasing energy. D) circulating energy.

Physics

2 answers:

olganol [36]3 years ago

5 0

Realizing energy.......

Mamont248 [21]3 years ago

4 0

The correct answer to the question is B) Absorbing energy.

EXPLANATION:

As per our question, the substance is melting at constant pressure.

Melting is a process of phase change in which a solid substance is converted into liquid at its melting point. For instance, melting of ice.

The thermal energy of the liquid is more as compared to solid. Hence, the solid must have to absorb energy to be converted into liquid. The absorbed energy will be utilized in changing the solid into its corresponding liquid.

As melting is a process of phase change or state change, the temperature of the substance will be constant as long as total solid is not converted into liquid. Hence, the kinetic energy of the substance will be constant. So, the energy absorbed during melting will only change the configuration of the substance i.e the absorbed energy is converted into potential energy of the system.

Hence, the correct answer of the question is that energy is absorbed during melting.

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You have 4.9 g of an unknown substance. To identify the substance, you decide to measure its specific heat and find that it requ

kifflom [539]

The unknown substance can be lithium, which has a specific heat capacity of approximately $3.5 J/gK$ .

Explanation:

When heat energy is supplied to a certain substance, the temperature of the substance increases according to the equation:

$Q=mC_s \Delta T$

where

Q is the amount of energy supplied

m is the mass of the sample

$C_s$ is the specific heat capacity of the substance

$\Delta T$ is the change in temperature

In this problem, we have

m = 4.9 g is the mass

Q = 668.85 J is the specific heat capacity

$\Delta T = 39 K$ is the change in temperature

Solving for $C_s$ , we find the specific heat capacity of the substance:

$C_s = \frac{Q}{m\Delta T}=\frac{668.85}{(4.9)(39)}=3.5 J/gK$

Looking at tables of specific heat capacity, we can see that the unknown substance can be lithium, which has a specific heat capacity of approximately $3.5 J/gK$ .

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3 0

3 years ago

The Assignment: A fixed quantity of an ideal gas (R 0.28 kJ/kgK; Cv-0.71kJ/kgK) is expanded from an initial condition of 35 bar,

Nikolay [14]

Answer:

Index of expansion: 4.93

Δu = -340.8 kJ/kg

q = 232.2 kJ/kg

Explanation:

The index of expansion is the relationship of pressures:

pi/pf

The ideal gas equation:

p1*v1/T1 = p2*v2/T2

p2 = p1*v1*T2/(T2*v2)

500 C = 773 K

20 C = 293 K

p2 = 35*0.1*773/(293*1.3) = 7.1 bar

The index of expansion then is 35/7.1 = 4.93

The variation of specific internal energy is:

Δu = Cv * Δt

Δu = 0.71 * (20 - 500) = -340.8 kJ/kg

The first law of thermodynamics

q = l + Δu

The work will be the expansion work

l = p2*v2 - p1*v1

35 bar = 3500000 Pa

7.1 bar = 710000 Pa

q = p2*v2 - p1*v1 + Δu

q = 710000*1.3 - 3500000*0.1 - 340800 = 232200 J/kg = 232.2 kJ/kg

7 0

3 years ago

transmission electron microscopes that use high-energy electrons accelerated over a range from 40.0 to 100 kv are employed in ma

Gekata [30.6K]

The spatial limitations in Picometer for the given range of electrons would be around 50 picometers.

What is a transmission electron microscope?

A transmission electron microscope (TEM) is a type of microscope that uses a beam of high-energy electrons to produce detailed images of the structure of materials at the atomic or molecular scale. TEMs work by passing a focused beam of electrons through a thin sample and collecting the transmitted electrons on a fluorescent screen or an electronic detector. The interaction of the sample with the electrons results in the formation of an image that can be magnified and displayed on a computer monitor. TEMs are widely used in the fields of materials science, biology, and nanotechnology and can provide information about the structure, composition, and properties of materials with a high level and resolution.

According to the problem:

The spatial resolution of a transmission electron microscope (TEM) is determined by the size of the electron probe, which is directly related to the energy of the electrons. The higher the energy of the electrons is, the smaller the size of the probe is and the higher the spatial resolution.

At the lower end of the energy range of 40.0 kV, the spatial resolution of the TEM would be on the order of hundreds of nanometers. At the higher end of the range (100 kV), the spatial resolution would be on the order of tens of nanometers.

In general, TEMs with electron energy in the range of 40-100 kV are capable of resolving details down to around 50 picometers (pm). However, the actual spatial resolution will depend on various factors, such as the quality of the electron optics, the stability of the electron beam, and the sample preparation.

It's worth noting that TEMs with even higher electron energies (up to several hundred kV) are available, which can achieve spatial resolutions down to the sub-angstrom level (less than 0.1 pm). However, these instruments are much more expensive and complex to operate than TEMs with lower electron energies.

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10 months ago

.A box falls to the ground from a delivery truck traveling at 30 m/s. After hitting the road, it slides 45 m to

Romashka-Z-Leto [24]

Answer:

t = 3 seconds

Explanation:

Given that,

Initial speed, u = 30 m/s

Final speed, v = 0

It slides 45 m to rest.it take the box to come to rest

We need to find how long it take the box to come to rest.

Let a be the acceleration and t is time.

$v^2-u^2=2ad\\\\a=\dfrac{v^2-u^2}{2d}\\\\a=\dfrac{(30)^2-u^2}{2(45)}\\\\=10\ m/s^2$

Now finding time.

$t=\dfrac{v-u}{a}\\\\t=\dfrac{30-0}{10}\\\\t=3\ s$

So, the required time is 3 seconds.

8 0

3 years ago

How does the electric force between two charged participles change if one particle’s charge is reduced by a factor of 3?

Eva8 [605]

Answer:

ick

Explanation:

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3 years ago