Answer:
It's held together by the nuclear force.
Explanation:
There are <em>more</em> elemental forces than just the electromagnetic one. In this case, it is the nuclear force (called also strong force) the one that holds the nucleus together because it is stronger than the electromagnetic force over such short distances as the one inside the atomic nucleus.
The measurement of sound is in decibels.
A. Illustrates how a theory becomes a law
Answer:
Normal force, 
Explanation:
Let
is the weight of suitcase. A man attempts to pick up his suitcase by pulling straight up on the handle. The weight of the suitcase in downward direction. The normal force is acting in upward direction. Let F is the force with which it is pulled straight up.
So, the normal force is given by :

N = mg - F
mg is the weight of the suitcase.
Hence, this is the required solution.
Okay, so the density of water is 1g/cm3. In order for the cube to float, it has to be less than 1, and it will sink if it is more than 1 g/cm3. Use a triple beam balance to weigh the cube, looking at the metric ruler on the balance. Then, if the cube's density is more than 1, then you know it will float. If the density is less than 1, you know it will sink.
hope this helps, and I didn't know how to use the word "metric ruler"