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Alekssandra [29.7K]
3 years ago
12

Two objects must be in contact for them to exert a force on each other. True or False

Physics
1 answer:
nevsk [136]3 years ago
7 0

Answer:

False

Explanation:

This proposition is false because by example the sun exerts a force over the earth and them are not in contact

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Scientists plan to release a space probe that will enter the atmosphere of a gaseous planet. The temperature of the gaseous plan
ZanzabumX [31]
From my research, the image supports the question. From the graph given, we can construct the equation of the line using the two-point formula. Using the given value of 601 K, we can solve for the missing value of altitude.

y - y1 = [(y2 - y1)/(x2 - x1)](x- x1)
y - 147.52 = [ (567 - 147.54)/(78.11 - 18.4) ](x - 18.4)

Substituting y = 601 to solve for x:
601 - 147.52 = [ (567 - 147.54)/(78.11 - 18.4) ](x - 18.4<span>)
</span>x = 83

Therefore, the probe's instruments will fail at 83 kilometers.

5 0
4 years ago
Steam enters an adiabatic turbine steadily at 7 MPa, 5008C, and 45 m/s, and leaves at 100 kPa and 75 m/s. If the power output of
marusya05 [52]

Answer:

a) \dot m = 6.878\,\frac{kg}{s}, b) T = 104.3^{\textdegree}C, c) \dot S_{gen} = 11.8\,\frac{kW}{K}

Explanation:

a) The turbine is modelled by means of the First Principle of Thermodynamics. Changes in kinetic and potential energy are negligible.

-\dot W_{out} + \dot m \cdot (h_{in}-h_{out}) = 0

The mass flow rate is:

\dot m = \frac{\dot W_{out}}{h_{in}-h_{out}}

According to property water tables, specific enthalpies and entropies are:

State 1 - Superheated steam

P = 7000\,kPa

T = 500^{\textdegree}C

h = 3411.4\,\frac{kJ}{kg}

s = 6.8000\,\frac{kJ}{kg\cdot K}

State 2s - Liquid-Vapor Mixture

P = 100\,kPa

h = 2467.32\,\frac{kJ}{kg}

s = 6.8000\,\frac{kJ}{kg\cdot K}

x = 0.908

The isentropic efficiency is given by the following expression:

\eta_{s} = \frac{h_{1}-h_{2}}{h_{1}-h_{2s}}

The real specific enthalpy at outlet is:

h_{2} = h_{1} - \eta_{s}\cdot (h_{1}-h_{2s})

h_{2} = 3411.4\,\frac{kJ}{kg} - 0.77\cdot (3411.4\,\frac{kJ}{kg} - 2467.32\,\frac{kJ}{kg} )

h_{2} = 2684.46\,\frac{kJ}{kg}

State 2 - Superheated Vapor

P = 100\,kPa

T = 104.3^{\textdegree}C

h = 2684.46\,\frac{kJ}{kg}

s = 7.3829\,\frac{kJ}{kg\cdot K}

The mass flow rate is:

\dot m = \frac{5000\,kW}{3411.4\,\frac{kJ}{kg} -2684.46\,\frac{kJ}{kg}}

\dot m = 6.878\,\frac{kg}{s}

b) The temperature at the turbine exit is:

T = 104.3^{\textdegree}C

c) The rate of entropy generation is determined by means of the Second Law of Thermodynamics:

\dot m \cdot (s_{in}-s_{out}) + \dot S_{gen} = 0

\dot S_{gen}=\dot m \cdot (s_{out}-s_{in})

\dot S_{gen} = (6.878\,\frac{kg}{s})\cdot (7.3829\,\frac{kJ}{kg\cdot K} - 6.8000\,\frac{kJ}{kg\cdot K} )

\dot S_{gen} = 11.8\,\frac{kW}{K}

4 0
4 years ago
A box is given a push so that it slides across the floor. How far will it go, given that the coefficient of kinetic friction is
maksim [4K]
D = v^2 / 2ug

d=  3.5^2 / 0,15 x 9.8 m/s^2

the answer should be around 4.2m

hope this helps
8 0
3 years ago
PLEASE ANSWER ASAP I REALLY NEED HELP!!!!!!
Andrews [41]

Answer:

In thermodynamics, heat is transferred energy that moves between substances or systems because of their temperature difference. According to the first law of thermodynamic and the law of energy conversion s a form of energy, heat is cannot be created or destroyed only moves from one form to other.

The stone gets heat energy from fire and moves this heat energy or thermal energy to water as it cools off and the water warms up. Heat moves or is transferred spontaneously from the hot stone into the cold water. Eventually, the stone and water have the same temperature and water becomes heated. At the time of heat flowing out of the stone into the water, the heat energy became less ordered, due to spreading out through both the stone and the water. This is a net increase in entropy which is the second law of entropy.

4 0
3 years ago
Complete the following​
Furkat [3]

answer is down hera

3 0
3 years ago
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