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3 years ago

What causes the apparent motions of stars across the sky each night

Physics

1 answer:

densk [106]3 years ago

3 0

Answer:

Explanation:

for the motion every night, it is because the Earth spins on its axis.

for the changes over a year, this is because the Earth rotates around the sun.

for the changes over hundreds, thousands or millions of years, this is because the whole solar system (including the Earth, of course) rotates with all the other stars in our galaxy around the center of the galaxy. and each star system has its own orbit (similar to the planets in our solar system).

it is very rare to see objects outside of our galaxy without a telescope, but they change too over a long period of time, because our galaxy not only rotates by also moves through the universe, and these other objects move on their own too.

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if you apply a net force of 5 N on a cart with a mass of 5 kg, show that the acceleration is one meter per second squared

lina2011 [118]

$*\\
From\ Newton's\ third\ Law:\\\\
acceleration=\frac{Net\ force}{mass}\\\\
Net\ force=5N\\
mass=5kg\\\\
acceleration=\frac{5N}{5kg}=1\frac{m}{s^2}$

3 0

3 years ago

A hydraulic press has a safety feature which consists of a hydraulic cylinder with a piston at one end and a safety valve at the

Sergio039 [100]

Answer:

Explanation:

radius of cylinder r₁ = .02 m

radius of safety valve r₂ = .0075 m

force exerted by spring on safety valve = 950 x .0085 = 8.075 N .

Force required on piston of cylinder = F

Applying Pascal's law

8.075 / 3.14 x .0075² = F / 3.14 x .02²

F = 8.075 x .02² / .0075²

= 8.075 x 7.111

= 57.42 N .

6 0

3 years ago

A supplier wants to make a profit by buying metal by weight at one altitude and selling it at the same price per pound weight at

Veronika [31]

The correct option is C.

In physics, the gravitational law makes us to understand that gravity change with altitude. The higher the altitude, the more the gravity one will experiences. Change in altitude also produce change in weight but all these changes are not really significant. Therefore, there will be no significant difference between weighing metals at different altitude, this is because the effect of gravity on them will be the same.

3 0

3 years ago

When atoms form a bond, it is usually because each atom acquires a more stable arrangement of electrons in its electron shells.

liraira [26]

C. Usually when an atom loses or gains an electron, it is because it is trying to satisfy the Octet Rule. The Octet Rule states that an atom is at its stablest when it has 8 valence electrons (two in helium's case)

If you look on the periodic table, elements on the left (Alkaline Metals) are the most reactive because they only have one valence electron (or electron in the outer shell). Elements on the right (Noble Gases) are the least reactive because they have a full outer shell of 8 valence electrons.

Later on you will find that as stability decreases as you go down the periodic table but that is a discussion for a different time.

4 0

3 years ago

Read 2 more answers

6. As the sky diver's fall the______energy is converted into _______.

notka56 [123]

Answer: B

D makes no sense because energy is created so we can remove that. C also makes no sense because if energy is not created how did it get destroyed if there's no energy in the first place. This leaves us with a and B the correct answer is B because energy is created and cannot be destroyed.

3 0

3 years ago