The oldest way ... the way we've been using as long as we've been
walking on the Earth ... has been to use plants. Plants sit out in the
sun all day, capturing its energy and using it to make chemical compounds.
Then we come along, cut the plants down, and eat them. Our bodies
rip the chemical compounds apart and suck the solar energy out of them,
and then we use the energy to walk around, sing, and play video games.
Another way to capture the sun's energy is to build a dam across a creek
or a river, so that the water can't flow past it. You see, it was the sun's
energy that evaporated the water from the ocean and lifted it high into
the sky, giving it a lot of potential energy. The rain falls on high ground,
up in the mountains, so the water still has most of that potential energy
as it drizzles down the river to the ocean. If we catch it on its way, we
can use some of that potential energy to turn wheels, grind our grain,
turn our hydroelectric turbines to get electrical energy ... all kinds of jobs.
A modern, recent new way to capture some of the sun's energy is to use
photovoltaic cells. Those are the flat blue things that you see on roofs
everywhere. When the sun shines on them, they convert some of its
energy into electrical energy. We use some of what they produce, and
we store the rest in giant batteries, to use when the sun is not there.
Government as an academic field of study is a vast subject, encompassing political institutions and political theories. ... Government allows for civil order by creating laws and protecting its citizens. In order to ensure enforcement of laws, government also creates punishments for those who break the law.
-- <u><em>Current is measured in amps.</em></u> (You can use any symbol you want to represent current, but the most common one is " I ", not "Δ".)
-- <u><em>The relationship between current, voltage, and resistance is mathematically defined by Ohm's Law. </em></u>
-- <u><em>Current is the flow of electrons through a circuit.</em></u>
-- (Ohm's Law is NOT mathematically represented by the equation V=I/R.) <u><em>It should be V = I · R</em></u> .
(When solving for Resistance in a circuit and both voltage and current are known values, the equation I =V*R is not true, and not the way to solve it.) <u><em>If the resistance is what you're looking for, then the equation to use is </em></u><u><em>R = V / I</em></u><u><em> . </em></u>
<em>-- </em><u><em>If the voltage in a circuit is increased, the current will also increase.</em></u>
Incomplete Question.The Complete question is
The Earth spins on its axis and also orbits around the Sun. For this problem use the following constants. Mass of the Earth: 5.97 × 10^24 kg (assume a uniform mass distribution) Radius of the Earth: 6371 km Distance of Earth from Sun: 149,600,000 km
(i)Calculate the rotational kinetic energy of the Earth due to rotation about its axis, in joules.
(ii)What is the rotational kinetic energy of the Earth due to its orbit around the Sun, in joules?
Answer:
(i) KE= 2.56e29 J
(ii) KE= 2.65e33 J
Explanation:
i) Treating the Earth as a solid sphere, its moment of inertia about its axis is
I = (2/5)mr² = (2/5) * 5.97e24kg * (6.371e6m)²
I = 9.69e37 kg·m²
About its axis,
ω = 2π rads/day * 1day/24h * 1h/3600s
ω= 7.27e-5 rad/s,
so its rotational kinetic energy
KE = ½Iω² = ½ * 9.69e37kg·m² * (7.27e-5rad/s)²
KE= 2.56e29 J
(ii) About the sun,
I = mR²
I= 5.97e24kg * (1.496e11m)²
I= 1.336e47 kg·m²
and the angular velocity
ω = 2π rad/yr * 1yr/365.25day * 1day/24h * 1h/3600s
ω= 1.99e-7 rad/s
so
KE = ½ * 1.336e47kg·m² * (1.99e-7rad/s)²
KE= 2.65e33 J
<span>Sea breeze can happen during hot summer days because of the
uneven heating rates of water and land.
The land surface heats up faster than the surface of the water during the
day. At this rate, the air above the
land grows warmer than the air atop the ocean. Warmer air is always lighter
than cooler air. As a consequence, warm air is pushed upward causing it to
rise. With this, warmer air rises over the land. As warm air rises over the
land, cooler air over the ocean flows over the land surface to change or
replace the rising warm air.</span>
