Actually, they're not. There's a group of stars and constellations arranged
around the pole of the sky that's visible at any time of any dark, clear night,
all year around. And any star or constellation in the rest of the sky is visible
for roughly 11 out of every 12 months ... at SOME time of the night.
Constellations appear to change drastically from one season to the next,
and even from one month to the next, only if you do your stargazing around
the same time every night.
Why does the night sky change at various times of the year ? Here's how to
think about it:
The Earth spins once a day. You spin along with the Earth, and your clock is
built to follow the sun . "Noon" is the time when the sun is directly over your
head, and "Midnight" is the time when the sun is directly beneath your feet.
Let's say that you go out and look at the stars tonight at midnight, when you're
facing directly away from the sun.
In 6 months from now, when you and the Earth are halfway around on the other
side of the sun, where are those same stars ? Now they're straight in the
direction of the sun. So they're directly overhead at Noon, not at Midnight.
THAT's why stars and constellations appear to be in a different part of the sky,
at the same time of night on different dates.
I believe that it is the first one just a guess tho. So don't trust me, just in case
Horizontal component = (10N) · sin (20°) = 3.42... N (rounded)
Vertical component = (10N) · cos (20°) = 9.39... N (rounded)
Answer:
Yes, the calorie can be expressed in SI units
Explanation:
1 calorie (1 cal) is defined as the amount of heat energy that must be supplied to 1 gram of water in order to raise its temperature by 1 degree Celsius (
.
The calorie is not a unit of the International System (SI): the SI unit for the energy is the Joule (J).
However, it is possible to convert energy from calories to Joules, and viceversa. In fact, the conversion factor between the two units is:
1 calorie = 4.184 Joules
So, to convert from calories to Joules we simply multiply by 4.184, while if we want to convert from Joules to calories, we just divide by 4.184.
Answer:
6787.5 V
Explanation:
From the question,
P = IV..................... Equation 1
Where P = Power, I = rms current, V = rms voltage.
make V the subject of the equation
V = P/I................. Equation 2
Given: P = 1500 W, I = 6.4/√2 = 4.525 A
Substitute these values into equation 2
V = 1500(4.525)
V = 6787.5 V
Hence the rms voltage = 6787.5 V
