A). Earth completes one rotation on its rotation axis
every (3 minutes and 56 seconds less than 24 hours).
This causes night and day. It's rotation, not precession.
B). Earth completes one orbital revolution around the sun
every (365 plus a little bit) days. It's revolution, not precession.
C). I'm not sure what happens on a cycle of 512 years.
It may have something to do with the moon. But whatever
it is, it's not precession.
D). When you spin a top and it starts to run down, the first
thing that happens is that the handle of the top, or the point
on top of the top, starts moving in a circle. That's precession.
That's what the Earth's axis is doing. The north pole points
toward the north star (Polaris) now. But the north pole is
actually drawing out a big circle in the sky, and other stars
will become the "north star" far in the future.
The north pole draws out a full circle in the sky, roughly
once every 26,000 years. That's precession.
Light<span> refracts whenever it </span>travels<span> at an angle into a substance with a </span>different<span>refractive index (optical density). This change of direction is </span>caused<span> by a change in speed. For example, when </span>light travels<span> from air into water, it slows down, causing it to continue to travel at a </span>different<span> angle or direction.</span>
Answer:
Having a bigger angle above the horizontal
Explanation:
Applying the energy conservation theorem:
The kinetic energy is reduced because of the work done by the friction force.
The friction force is given by:
so the friction force depends on the Normal force, because the slide has an angle the normal force is given by:
So when the angle of the slide is bigger, the friction force decreases, for example:
for 45 degrees:
for 75 degrees:
as you can see if the angle is bigger above the horizontal, the friction force is reduced and so the work done by that force. We didn't have to change the height of the slide, so the potential gravitational energy remains the same.
When you're talking about gravity, it's easy to identify the equal
opposite forces.
Gravity ALWAYS produces an equal pair of opposite forces.
They both act between the centers of the two objects, one in
each direction.
Consider the equal pair of opposite gravitational forces between
you and the Earth. One force acts on you, and draws you toward
the center of the Earth. We call that force "your weight".
The other one acts on the Earth, and draws it toward the center
of you. Hardly anybody ever talks about that one, but the two
forces are equal ... your weight on Earth is equal to the Earth's
weight on you !
