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AysviL [449]
3 years ago
9

Heat is transferred at a rate of 2 kW from a hot reservoir at 800 K to a cold reservoir at 300 K. Calculate the rate at which th

e entropy of the two reservoirs changes and determine if the second law is satisfied
Physics
1 answer:
vekshin13 years ago
6 0

Answer:

0.00417 kW/K or 4.17 W/K

Second law is satisfied.

Explanation:

Parameters given:

Rate of heat transfer, Q = 2kW

Temperature of hot reservoir, Th = 800K

Temperature of cold reservoir, Tc = 300K

The rate of entropy change is given as:

ΔS = Q * [(1/Tc) - (1/Th)]

ΔS = 2 * (1/300 - 1/800)

ΔS = 2 * 0.002085

ΔS = 0.00417 kW/K or 4.17 W/K

Since ΔS is greater than 0, te the second law of thermodynamics is satisfied.

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A ball falls from the top of a building. As it falls, its speed increases. Which type of energy is the ball gaining as it falls?
Elina [12.6K]
<h2>Hello!</h2>

The answer is: B. Kinetic energy

<h2>Why?</h2>

Since the ball is falling, speed increases because the gravity acceleration is acting. When speed increases, the kinetic energy increases too, so the ball is gaining kinetic energy.

The gravity acceleration is equal to 9.81\frac{m}{s^{2}}, it means that when falling, the ball will increase it's speed 9.81m every second.

We can calculate the kinetic energy by using the following formula:

KE=\frac{1}{2}*m*v^{2}

Where:

m=mass\\v=velocity

Have a nice day!

<h2 />
5 0
3 years ago
Deep in the interiors of the giant planets, water is still a liquid even though the temperatures are tens of thousands of degree
Nataliya [291]

Answer:

High pressure inside the giant planet

Explanation:

As we move in the interior of the giant planet, the pressure and temperature in the interior of the planet increases. Since, the giant planets have hardly any solid surface and thus they are mostly constituted of atmosphere.

Also, the gravitational forces keep even the lightest of the matter bound in it contributing to the large mass of the planet.

If we look at the order of the magnitude of the temperature of these giant planets than nothing should be able to stay in liquid form but as the depth of the planet increases with the increase in temperature, pressure also increases which keeps the particle of the matter in compressed form.

Thus even at such high order of magnitude water is still found in liquid state in the interior of the planet.

7 0
3 years ago
Help ASAP with equation and answer pls. Numbers 2 3 4
scoray [572]

Answer:

2. 200N

3.50kg

4.700N

Explanation:

Weight is another word for the force of gravity

Weight is a force that acts at all times on all objects near Earth.

F=m*g

where g=acceleration due to gravity

2. due to the gravitational fields of the earth , assume gravitational acceleration=10m/s2

F=20*10= 200N

3.same as above

mass=Force/gravitational acceleration

mass=500/10 = 50kg

4.force=mass*gravitational acceleration

force=70*10=700N

8 0
3 years ago
A car battery can deliver up to 75 amps of current at a voltage of 12 volts. How much power is this?
Alex_Xolod [135]
A.900 watts That would be your correct answer 
4 0
3 years ago
Read 2 more answers
A dentist’s drill starts from rest. After 4.28 s of constant angular acceleration it turns at a rate of 28940 rev/min. Find the
mylen [45]

Answer:

Angular acceleration, is 708.07\ rad/s^2

Explanation:

Given that,

Initial speed of the drill, \omega_i=0

After 4.28 s of constant angular acceleration it turns at a rate of 28940 rev/min, final angular speed, \omega_f=28940\ rev/min=3030.58\ rad/s

We need to find the drill’s angular acceleration. It is given by the rate of change of angular velocity.

\alpha =\dfrac{\omega_f}{t}\\\\\alpha =\dfrac{3030.58\ rad/s}{4.28\ s}\\\\\alpha =708.07\ rad/s^2

So, the drill's angular acceleration is 708.07\ rad/s^2.

4 0
2 years ago
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