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Serga [27]
3 years ago
7

sunlight, wind, and running water are essentially "free." Yet renewable energy sources are a very small part of our energy consu

mption. Why is this?
Physics
2 answers:
dimulka [17.4K]3 years ago
7 0
The heat and energy of coal burning is more easier and more efficient to turn into electricity than any method using renewable resources. 
lilavasa [31]3 years ago
4 0

Explanation:

oop hello UwU OwO

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If the mass of a planet is 0.231 mE and its radius is 0.528 rE, estimate the gravitational field g at the surface of the planet.
crimeas [40]

Answer:

8.1 m/s^2

Explanation:

The strength of the gravitational field at the surface of a planet is given by

g=\frac{GM}{R^2} (1)

where

G is the gravitational constant

M is the mass of the planet

R is the radius of the planet

For the Earth:

g_E = \frac{GM_E}{R_E^2}=9.8 m/s^2

For the unknown planet,

M_X = 0.231 M_E\\R_X = 0.528 R_E

Substituting into the eq.(1), we find the gravitational acceleration of planet X relative to that of the Earth:

g_X = \frac{GM_X}{R_X^2}=\frac{G(0.231M_E)}{(0.528R_E)^2}=\frac{0.231}{0.528^2}(\frac{GM_E}{R_E^2})=0.829 g_E

And substituting g = 9.8 m/s^2,

g_X = 0.829(9.8)=8.1 m/s^2

3 0
3 years ago
Calculate the size of the image of a tree that is 8m high and 80 m a pinhole camera that is 20 cm long . what is its magnificati
Vladimir79 [104]

1) Size of the image: 2 cm

In order to calculate the size of the image, we can use the following proportion:

p:q = h_o : h_i

where

p = 80 m is the distance of the tree from the pinhole

q = 20 cm = 0.2 m is the distance of the image from the pinhole

h_o = 8 m is the heigth of the object

h_i is the height of the image

By re-arranging the proportion, we find

h_i = \frac{h_o \cdot q}{p}=\frac{(8 m)(0.2 m)}{80 m}=0.02 m=2 cm


2) Magnification: 0.0025

The magnification of a camera is given by the ratio between the size of the image and the size of the real object:

M=\frac{h_i}{h_o}

so, in this problem we have

M=\frac{0.02 m}{8 m}=0.0025


4 0
3 years ago
Which of the following would be used in luminosity calculations?
Daniel [21]

Answer:

1) joule

2) kgm^{2}/s^{2}

3) 10\%

Explanation:

1) Luminosity is the <u>amount of light emitted</u> (measured in Joule) by an object in a unit of<u> time</u> (measured in seconds). Hence in SI units luminosity is expressed as joules per second (\frac{J}{s}), which is equal to Watts (W).

This amount of light emitted is also called radiated electromagnetic power, and when this is measured in relation with time, the result is also called radiant power emitted by a light-emitting object.

Therefore, if we want to calculate luminosity the Joule as a unit will be used.

2) Work W is expressed as force  F multiplied by the distane  d :

W=F.d

Where force has units of  kgm/s^{2} and distance units of m.

If we input the units we will have:

W=(kgm/s^{2})(m)

W=kgm^{2}/s^{2}  This is 1Joule (1 J) in the SI system, which is also equal to 1 Nm

3) The formula to calculate the percent error is:

\% error=\frac{|V_{exp}-V_{acc}|}{V_{acc}} 100\%

Where:

V_{exp}=7.34 (10)^{-11} Nm^{2}/kg^{2} is the experimental value

V_{acc}=6.67 (10)^{-11} Nm^{2}/kg^{2} is the accepted value

\% error=\frac{|7.34 (10)^{-11} Nm^{2}/kg^{2}-6.67 (10)^{-11} Nm^{2}/kg^{2}|}{6.67 (10)^{-11} Nm^{2}/kg^{2}} 100\%

\% error=10.04\% \approx 10\% This is the percent error

8 0
3 years ago
Optical tweezers use light from a laser to move single atoms and molecules around. Suppose the intensity of light from the tweez
WITCHER [35]

Answer:

Explanation:

a )

If it is totally absorbed pressure is calculated as follows .

Pressure = I / c where I is intensity of light falling .

= 1000 / 3 x 10⁸

= 3.33 x 10⁻⁶ N / m²

b ) weight of tritium atom

=  3 x 1.67 x 10⁻²⁷ kg

acceleration = force / mass

=    3.33x 10⁻⁶ / 3 x 1.67 x 10⁻²⁷

= .6646 x 10²¹ m /s²

= 66.46 x 10¹⁹ m / s²

7 0
2 years ago
I didnt want my question public i made a mistake i want it taken down
mrs_skeptik [129]
Then report it and it might be taken down
5 0
2 years ago
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