The cart's force is only in reaction to the horse's force so it does not define direction of movement.
Electromagnetic waves travel through a vacuum, Because it has an electric and a magnetic component in it.
<u>Explanation:</u>
The vibration that is created in an electric charge is the cause for the creation of an electromagnetic wave. The electromagnetic waves contains a magnetic and an electric component in it because of this vibration. The transportation of the energy at 3.00 x 108 m/s speed in an empty space.
The electric and magnetic components that are present in an electromagnetic wave is called fields. There is a vibration at an angle of 90 degree by these fields with respect to the wave motion. The light speed remains unchanged.
When you say "heavy", you're talking about the gravitational force
between that object and another object, so it depends on what the
"other object" is.
If the "other object" is, let's say, the sun, then the gravitational attraction
between the Earth and sun is about 80 times as much as the gravitational
attraction between the Moon and sun, because the Earth has about 80 times
the mass of the Moon.
But if, somehow, the weight you have in mind is the gravitational attraction
between the Earth and the Moon, then those forces are equal. The force
of gravity between two objects depends on the product of both masses,
and it's equal in both directions.
If that isn't clear to you, let me give you this additional fact that's guaranteed
to knock you even further off-balance:
Your weight on the Earth is determined by the product of
(your mass) times (the Earth's mass).
The Earth's weight on you is determined by the product of
(your mass) times (the Earth's mass).
Your weight on Earth is the same as the Earth's weight on you.
Would you like to prove it ?
-- Turn the bathroom scale upside-down, so that the step-pad
is on the floor.
-- Then step on it, so that you're standing on the bottom, which
is facing up.
-- If you placed a little mirror on the floor, so that you can read
the numbers, which are facing down toward the floor, you'll
read your own weight, even though with the scale upside-down,
you're weighing the Earth on you.
