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oksian1 [2.3K]
3 years ago
9

A simple machine has efficiency 90%. What does it mean? No machine has 109 efficiency,why?​

Physics
2 answers:
Marrrta [24]3 years ago
7 0

Answer:

<em>Efficiency of a machine is 90% this means that the total energy produced to the machine only 90% is useful and given as a output.</em>

<em>Machines are not 100% efficient because some of the work done by a machine is used to overcome friction</em>

Novay_Z [31]3 years ago
7 0

Explanation:

A simple machine has efficiency 90% means that 10% of the applied effort is wasted due to overcoming friction and 90% of the applied force is used in doing useful work .No machinr has hundred percent efficiency because every machine is affected by overcoming friction .

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In this problem, you will answer several questions that will help you better understand the moment of inertia, its properties, a
scoundrel [369]

Answer:

a)  Total mass form, density and axis of rotation location are  True

b)   I = m r²

Explanation:

a) The moment of inertia is the inertia of the rotational movement is defined as

       I = ∫ r² dm

Where r is the distance from the pivot point and m the difference in body mass

In general, mass is expressed through density

        ρ = m / V

        dm = ρ dV

From these two equations we can see that the moment of inertia depends on mass, density and distance

Let's examine the statements, the moment of inertia depends on

- Linear speed       False

- Acceleration angular False

-  Total mass form True

-  density True

- axis of rotation location   True

b) we calculate the moment of inertia of a particle

For a particle the mass is at a point whereby the integral is immediate, where the moment of inertia is

          I = m r²

4 0
3 years ago
A heat pump is to be used for heating a house in winter. The house is to be maintained at 70°F at all times. When the temperatur
Anna35 [415]

Answer:

\dot{W_{H} } = 4244.48 Btu/h

Explanation:

Temperature of the house, T_{H} = 70^{0} F

Convert to rankine, T_{H} = 70^{0}+ 460 = 530 R

Heat is extracted at 40°F i.e T_{L} = 40^{0}F  = 40 + 460 = 500 R

Calculate the coefficient of performance of the heat pump, COP

COP = \frac{T_{H} }{T_{H} - T_{L}  } \\COP = \frac{530 }{530 - 500  }\\ COP = \frac{530}{30} \\COP = 17.67

The minimum power required to run the heat pump is given by the formula:

\dot{W_{H} } = \frac{\dot{Q_{H} }}{COP} \\...............(*)

Where the heat losses from the house, \dot{Q_{H} } = 75,000 Btu/h

Substituting these values into * above

\dot{W_{H} } = \frac{75000}{17.67} \\ \dot{W_{H} } = 4244.48 Btu/h

3 0
3 years ago
How do you do to your question to see if its answered?
Jobisdone [24]

Answer:

Go in notifications, it'll show if it was answered. If it doesn't show that a person answered it, wait a while, someone might respond :)

Explanation:

On the Top right of your screen, theres a bell button. Click that and it will show all the notifications. it will also show if a person answered it.

It will pop up like

*random username*  answered your question! ]

Hope this helped

6 0
3 years ago
Read 2 more answers
What is the IEEE 802.11a center frequency in GHz, and what are its max/min data rates in Mbps? What is the IEEE 802.11b center f
kogti [31]

Explanation:

What is IEEE 802.11?

IEEE 802.11 is a set of WLAN standards for communication developed by the Institute for Electrical and Electronics Engineers (IEEE) and is unarguably most widely used WLAN technology.

Features: IEEE 802.11a

  • The operating frequency band is 5 GHz.
  • The maximum theoretical data rate is 54 Mbps, the typical throughput is around 25 Mbps and minimum data rate is 6 Mbps.
  • It can support 64 users per access point.

Features: IEEE 802.11b

  • The operating frequency band is 2.4 GHz.
  • The maximum theoretical data rate is 11 Mbps but typical throughput is around 6 Mbps and minimum data rate is 1 Mbps.
  • It can support 32 users per access point.

Wireless Coverage IEEE 802.11a Vs IEEE 802.11b:

  • Signal coverage is one of the most important factors among users.
  • The transmission range of IEEE 802.11a is not greater than 100 ft in indoor setting whereas IEEE 802.11b has a superior performance in this regard with transmission range up to 150 ft in indoor setting.
  • The data rate has a direct relation with the access point coverage area, a higher data rate means less coverage area and a lower data rate results in increased coverage.
8 0
3 years ago
In world war 1 , Multiple reflection was used in submarines. How multiple reflection works and helps in such situation?
prisoha [69]

<u>Answer:</u>

Submarines use a device called Periscope that uses the concept of multiple reflections and help us see objects above the water surface.

<u>Explanation:</u>

When a light ray falls on a reflecting surface like a mirror, it gets reflected.  In multiple reflections, the incident light ray is made to reflect multiple times by arranging the reflecting surfaces in different ways.

In submarines, we use Periscope, which is a long tube like structure. The long tube is bent at ends. It uses two simple mirrors which are placed parallel to each other at an angle of 45 degrees. The light from one mirror gets reflected to the other mirror, thus causing a multiple reflection.

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