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3 years ago

Select the choice that best completes the following sentence. Simple machines

Physics

2 answers:

AnnZ [28]3 years ago

5 0

Are the devices that change the magnitude and/or direction of a force.

morpeh [17]3 years ago

3 0

Simple machines are pullys ramps and more thaks 4 pointz

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Assume that in 2010 the United States will need 2.0×1012 watts of electric power produced by thousands of 1000 MW power plants.

Alex73 [517]

Answer:

1752.14 tonnes per year.

Explanation:

To solve this exercise it is necessary to apply the concepts related to power consumption and power production.

By conservation of energy we know that:

$\dot{P} = \bar{P}$

Where,

$\dot{P} =$ Production of Power

$\bar{P} =$ Consumption of power

Where the production of power would be,

$\dot{P} = m \dot{E}\eta$

Where,

m = Total mass required

$\dot{E} =$ Energy per Kilogram

$\eta =$ Efficiency

The problem gives us the aforementioned values under a production efficiency of 45%, that is,

$\dot{P} = \bar{P}$

$m \dot{E}\eta = \bar{P}$

Replacing the values we have,

$m(8*10^13)(0.45) = 2*10^{12}$

Solving for m,

$m = \frac{ 2*10^{12}}{(8*10^13)(0.45)}$

$m = 0.0556 \frac{kg}{s}$

We have the mass in kilograms and the time in seconds, we need to transform this to tons per year, then,

$m = 0.556\frac{kg}{s}*(\frac{3.1536*10^7s}{1year})(\frac{1ton}{1000kg})$

$m = 1752.14$ tonnes per year.

8 0

3 years ago

Potential energy is related to the speed of an object.<br><br><br> True or False

adelina 88 [10]

Answer:

False

Explanation:

Potential energy is stored energy, so it is not in motion. Kinetic energy is the energy in motion.

4 0

3 years ago

Electrons may be __________ or __________ other atoms.

jeka94

C. in a covalent bond, they are shared by two atoms, while in an ionic bond, they are transferred

4 0

3 years ago

ad for the distance from the sun tothe earth is 1.5 x 10"m. how long does it take for light from ths sun to reach the eath? give

Alexandra [31]

Answer:

About 8.3 minutes

Explanation:

Use the formula for velocity as the distance covered by the light divided the time it takes: $[tex]velocity=\frac{distance}{time}$ [/tex]

Use the information about the speed of light in vacuum: $300000000 \frac{m}{s} = 3*10^{8} \frac{m}{s}$

and the information you are given regarding the distance between Sun and Earth: $1.5 * 10^{11} m$

to solve the first velocity equation for the unknown time "t":

$velocity=\frac{distance}{time} \\3*10^8\frac{m}{s} =\frac{1.5*10^11 m}{t} \\t=\frac{1.5*10^11 }{3*10^8} s= 500 s$

we can convert second into minutes by dividing by 60: 500 s = 500/60 minutes = 8.3333... minutes

5 0

3 years ago

Help i dont know what it is

uysha [10]

Answer:

object B of 30 kg

Explanation:

an example be..let object B is earth and object A is moon ....the gravitational force of earth is greater than moon because the higher the mass the more the gravitational force towards it.

7 0

3 years ago