Because the polar regions receive low-angle insolation.
Insolation is the amount of solar radiation received by a given area. The Sun is always low on the horizon. The low Sun angle makes the beam of solar radiation to travel a longer distance from upper troposphere to reach earth's surface as compared to when it is directly overhead. In this case, the radiations are scattered and reflected more by the atmosphere and spread over a larger area. Thus, the intensity of solar radiation is very less at polar regions than near the equatorial region. This is the reason of very cold climates at polar regions.
The acceleration of an object depends on the mass of the object and the amount of the force applied to it. It states that the acceleration of an object increases with increased force and decreases with increased mass.
Let's start with the total amount of energy available for the whole scenario:
Some kind of machine gave the coaster a bunch of potential energy by
dragging it up to the top of a 45m hill,and that's the energy is has to work with.
Potential energy = (M) (G) (H) = (800) (9.8) (45) = 352,800 joules
It was then given an extra kick ... enough to give it some kinetic energy, and
start it rolling at 4 m/s.
Kinetic energy = (1/2) (M) (V)² = (1/2) (800) (4)² = 6,400 joules
So the coaster starts out with (352,000 + 6,400) =<em> </em><u><em>359,200 joules</em></u><em> </em>of energy.
There's no friction, so it'll have <u>that same energy</u> at every point of the story.
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Skip the loop for a moment, because the first question concerns the hill after
the loop. We'll come back to it.
The coaster is traveling 10 m/sat the top of the next hill. Its kinetic energy is
(1/2) (M) (V)² = (400) (10)² = 40,000 joules.
Its potential energy at the top of the hill is (359,200 - 40,000) = 319,200.
PE = (M) (G) (H)
319,200 = (800) (9.8) (H)
H = (319,200) / (800 x 9.8) = <em>40.71 meters</em>
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Now back to the loop:
You said that the loop is 22m high at the top. The PE up there is
PE = (M) (G) (H) = (800) (9.8) (22) = 172,480 joules
So the rest is now kinetic. KE = (359,200 - 172,480) = 186,720 joules.
KE = (1/2) (M) (V)² = 186,720
(400) (V)² = 186,720
V² = 186,720 / 400 = 466.8
V = √466.8 = <em>21.61 m/s</em>
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Now it looks like there should be another question ... that's why they
bothered to tell you that the end is 4m off the ground. They must
want you to find the coaster's speed when it gets to the end.
At 4m off the ground, PE = (M) (G) (H) = (800) (9.8) (4) = 31,360 joules.
The rest will be kinetic. KE = (359,200 - 31,360) = 327,840 joules
KE = (1/2) (M) (V)² = 327,840
400 V² = 327,840
V² = 327,840 / 400 = 819.6
V = √819.6 = <em>28.63 m/s</em> at the end
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If the official answers in class are a little bit different from these,
it'll be because they used some different number for Gravity.
I used '9.8' for gravity, but very often, they use '10' .
If the official answers in class are way way different from these,
then I made one or more big mistakes somewhere. Sorry.
answer:
1.8E-15C/1.6E-19=11,250
Explanation:
The biochemistry that takes place inside cells depends on various elements, such as sodium, potassium, and calcium, that are dissolved in water as ions. These ions enter cells through narrow pores in the cell membrane known as ion channels. Each ion channel, which is formed from a specialized protein molecule, is selective for one type of ion. Measurements with microelectrodes have shown that a 0.30-nm-diameter potassium ion ({\rm{{\rm K}}}^{\rm{ + }} ) channel carries a current of 1.8 {\rm pA}.