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Black_prince [1.1K]
3 years ago
10

How long have simple machines been around?

Engineering
1 answer:
lesantik [10]3 years ago
3 0

Answer:They have been around senses the 3 century BC

Explanation:

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I’m doing a project on renewable energy. There are 6 energy sources. Solar, wind, geothermal, hydroelectric, tidal, and biomass.
nalin [4]

Answer:

"Biofuels"

Explanation:

I don't know if this counts but I guess it's not one of those.

6 0
3 years ago
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What different tests did the team perform to come up with a workable design?
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They ran different shapes and materials through a wind tunnel to see which shape and material would decrease energy output so that it takes in equal COthan it puts out.
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4 years ago
Steam enters a turbine in a Rankine cycle power plant at 200 psia and 500 °F. a) Calculate the isentropic thermal efficiency if
Aleks04 [339]

Answer:

η=0.19=19% for p=14.7psi

η=0.3=30% for p=1psi

Explanation:

enthalpy before the turbine, state: superheated steam

h1(p=200psi,t=500F)=2951.9KJ/kg

s1=6.8kJ/kgK

Entalpy after the turbine

h2(p=14.7psia, s=6.8)=2469KJ/Kg

Entalpy  before the boiler

h3=(p=14.7psia,x=0)=419KJ/Kg

Learn to pronounce

the efficiency for a simple rankine cycle is

η=\frac{h1-h2}{h1-h3}

η=(2951.9KJ/kg-2469KJ/Kg)/(2951.9KJ/kg-419KJ/Kg)

η=0.19=19%

second part

h2(p=1psia, s=6.8)=2110

h3(p=1psia, x=0)=162.1

η=(2951.9KJ/kg-2110KJ/Kg)/(2951.9KJ/kg-162.1KJ/Kg)

η=0.3=30%

7 0
4 years ago
A body whose velocity is constant has a. positive acceleration b. negative acceleration g. zero acceleration d. all of the above
adoni [48]

Answer:

option (c) is the correct answer which is zero acceleration.

Explanation:

It is given in the question that the velocity is constant.

Now,

the options are provided in relation to the acceleration.

We know,

acceleration is rate of change of velocity per unit time i.e

acceleration = \frac{dV}{dt}

since, the change in velocity is given to be zero,

thus, dV/dt = 0

hence,  

acceleration = 0

therefore, option (c) is the correct answer which is zero acceleration.

4 0
4 years ago
What type of lights should you use if a vehicle is approaching you from the 1 point
Pepsi [2]

Answer:

dim lights

Explanation:

5 0
3 years ago
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