Answer:
Grow up man, this is completely based on your curriculum, we would need your book to answer, and this has to be done by you.
Stairs don't have any power at all. All the energy used to climb them
has to come from your muscles.
An elevator gets its power from the electric motors that lift it. All YOU
have to do is stand there and look around.
All of this is a big part of the reason why elevators have become so
popular, and why no buildings with more than a few floors were built
before elevators were invented.
<span>The correct option is C. Gravity, and the complete sentence is: "The force of gravity is the force at which the Earth attracts another object towards itself". In fact, the force of gravity between two objects is given by
</span>

<span>
where G is the gravitational constant, m1 and m2 the masses of the two objects, r their separation. If we take the Earth as one of the two objects, then m1 represents the Earth's mass, m2 the mass of the object and r the distance between the center of Earth and the object, and F is the gravitational force at which the Earth attracts the object.</span>
The light must be either very dim or else non-existent.
We can't see the light wave or the label.
Answer:
Scientists have studied eclipses since ancient times. Aristotle observed that the Earth's shadow has a circular shape as it moves across the moon. He posited that this must mean the Earth was round. Another Greek astronomer named Aristarchus used a lunar eclipse to estimate the distance of the Moon and Sun from Earth