Answer:

Explanation:
If the collision is elastic and exactly head-on, then we can use the law of momentum conservation for the motion of the 2 balls
Before the collision

After the collision

So using the law of momentum conservation


We can solve for the speed of ball 1 post collision in terms of others:

Their kinetic energy is also conserved before and after collision


From here we can plug in 






The sentence can be completed as follows:
The wavelength of an electromagnetic waves is the spatial distance between two successive troughs.
Note that the wavelength of a wave can also measured as the spatial distance between two successive crests of the wave. Also note that the second part of the sentence ("also known as the period") is not true, because period is another thing (in fact, the period is the time interval between two successive troughs).
Explanation:
the table and the wooden block
<span>The salad dressing is known as a compound dressing. A compound is simply a combination, or mixture, of two or more ingrediants.
Physical properties include, density, hardness, melting, and boiling points. Flammability is considered a chemical property along with vapor, concentration, etc.
Wood is not a reliable conductor for heat, while Copper is considered the best.</span>