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Crazy boy [7]
3 years ago
6

Predict whether the changes in enthalpy, entropy, and free energy will be positive or negative for the melting of ice, and expla

in your predictions. How does temperature affect the spontaneity of this process?
Physics
1 answer:
BlackZzzverrR [31]3 years ago
4 0
  <span>Melting of ice is an endothermic process, meaning that energy is absorbed. When ice spontaneously melts, ΔH (change in enthalpy) is "positive". ΔS (entropy change) is also positive, because, becoming a liquid, water molecules lose their fixed position in the ice crystal, and become more disorganized. ΔG (free energy of reaction) is negative when a reaction proceeds spontaneously, as it happens in this case. Ice spontaneously melts at temperatures higher than 0°C. However, liquid water also spontaneously freezes at temperatures below 0°C. Therefore the temperature is instrumental in determining which "melting" of ice, or "freezing" of water becomes spontaneous. The whole process is summarized in the Gibbs free energy equation: 
ΔG = ΔH – TΔS</span>
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A bar magnet is placed on a table so that the north pole faces right.
Katena32 [7]

The correct answer is C. They are pointing right to left.


Explanation.

A magnet has two poles, a north pole and a south pole.  When dealing with magnets, we define the concept of a magnetic field. A magnetic field represents the effect of the magnet on magnetic materials and moving charges in the space around the magnet. For every magnet, the magnetic field lines always point away from the north pole of the magnet towards the south pole. Since the north pole of this magnet faces right, the magnetic field lines point towards the left.

The correct answer is C. They are pointing right to left.

5 0
4 years ago
Read 2 more answers
How are acceleration and velocity related
IRINA_888 [86]

Answer:

answer is C

Explanation:

acceleration is rate of changing velocity in a time

5 0
3 years ago
Two observers in different inertial reference frames moving relative to each other at nearly the speed of light see the same two
lions [1.4K]

Answer:

The correct answer is d Both the observer's are correct

Explanation:

We know by postulates of relativity that laws of physics are same in different inertial frames.

Thus for each of the frames they make observations related to their frames and since the observations are true for their individual frames they both are correct. But when we compare the two frames we need to use transformation equations to compare both the results.

3 0
3 years ago
With "normal" gravity, we used a potential energy of mgh. Now with the gravity that is more accurate over longer distances we us
Artemon [7]

Answer:

A general solution is \Delta U=mh\frac{GM}{r^{2}}\frac{r}{r+\Delta h} and a particualr case is mgh, it is just to distance around the radius Earth.

Explanation:

We can use a general equation of the potential energy to understand the particular and general case:

The potential energy is defined as U=-\int F\cdot dx, we know that the gravitational force is F=GmM/r^{2}, so we could find the potential energy taking the integral of F.

U=-GmM/r (1)

We can find the particular case, just finding the gravitational potential energy difference:

\Delta U=U_{f}-U_{i}. Here Uf is the potential evaluated in r+Δh and Ui is the potential evaluated in r.

Using (1) we can calculate ΔU.

\Delta U=-\frac{GmM}{r+\Delta h}+\frac{GmM}{r}

Simplifying and combining terms we have a simplified expression.

\Delta U=mh\frac{GM}{r^{2}}\frac{r}{r+\Delta h} (2)

Let's call g=\frac{GM}{r^{2}}. It is the acceleration due to gravity on the Earth's surface, if r is the radius of Earth and M is the mass of the Earth and we can write (2) as ΔU=mgh, but if we have distance grader than r we should use (2), otherwise, we could get incorrect values of potential energy.

I hope i hleps you!

3 0
4 years ago
A firefighter directs a stream of water from a fire hose at an angle of 40.0° above the horizontal. If the velocity of the strea
mina [271]

Answer: The time of motion of the stream of water is calculated as follows;

X = Vₓt

Explanation:

5 0
2 years ago
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