Electromagnetic waves about the size of a golf ball are used for
microwave radio communication and radar every day.
Electromagnetic waves that are about 4-1/2 inches long are used
in the microwave oven to heat leftover meatloaf and make popcorn .
Electromagnetic waves that are 10 times the size of an atom
are hard hard X-rays.
Electromagnetic waves that are the size of Earth's diameter
are used for ELF communications, including standard time
signals, and submarine communication.
Mechanical waves that are the same order of magnitude as
the Earth are seismic (earthquake) waves.
Gamma rays are electromagnetic waves with wavelengths in the
neighborhood of the same size as the atomic nucleus. To get
some idea of their frequency, just contemplate how long it would
take light ... (which can get to the moon in a couple of seconds) ...
to move from one side of an atomic nucleus to the other side.
If the force moving an object points at least partially in the opposite direction of the objects motion, the work is considered to be negative.
<u>Explanation:
</u>
Work done is the measure of displacements caused on an object by the amount of force acting on it. The work done can be positive or negative. If the direction of force acting on an object is along the direction of motion of the object then the work done is positive.
This is because, in this case the external force is helping the object to continue its state of motion. So, if the force acting on the object is in completely opposite or partially opposite direction to the direction of motion of the object, it will stop or slow down the motion of the object.
This kind of force will have negative direction to the motion of the object and hence the work done will also be negative.
A squared plus b squared equals c squared
Answer: Magnes
Explanation: Magnes found that the nails and buckle of his sandals and the tip of his staff were attracted to the rock he was standing on. He dug up the Earth to find lodestones. Lodestones contain magnetite, a natural magnetic material Fe3O4.
