1) Example of contact force: friction
2) Examples of non-contact forces: gravity and electromagnetic force
Explanation:
1)
Contact forces are forces that acts only when the objects involved are touching.
An example of contact force in the geosphere is friction. Friction is a force that acts when two objects slide past each other, and the surfaces of the two objects are in contact. Due to the presence of "microbumps" on the two surfaces, there is a resistive force opposing the motion of the two objects, and this force is called friction.
Friction also acts when an object is moving through a fluid, although it takes a different name: resistance. Also in this case, the resistance acts in the direction opposite to the motion of the object, slowing it down.
2)
Non-contact forces are forces that act from a distance, therefore they act even when the objects involved are not touching.
Examples of non-contact forces are:
- Gravitational force: this is an attractive force that acts between any object with mass. Its magnitude is directly proportional to the product of the masses of the two objects and inversely proportional to the square of the distance between the two objects.
- Electromagnetic force: this is a force exerted between electrically charged objects. Its magnitude is directly proportional to the product of the two charges and inversely proportional to the square of the distance between the charges. It can be attractive (if the charges have opposite sign) or repulsive (if the charges have same sign).
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Answer:
nine times as much.
Explanation:
K.E of A = 9 times K.E of B
Answer:

Explanation:
Here two charges are placed at distance "d" apart
now the net value of electric field at some position between two charges will be ZERO
so we will have
electric field due to charge 1 = electric field due to charge 2

Let the position where net field is zero will lie at distance "r" from q1

now we will have

now square root both sides

now we have

so we have

Answer:
It would not be possible the cohesion among water molecules by the polar covalent bonding.
Well, to understand this in a better way, let's begin by explaining that water is special due to its properties, which makes this fluid useful for many purposes and for the existence of life.
In this sense, one of the main properties of water is cohesion (molecular cohesion), which is the attraction of molecules to others of the same type. So, water molecule (
) has 2 hydrogen atoms attached to 1 oxygen atom and can stick to itself through hydrogen bonds.
How is this possible?
By the polar covalent bonding, a process in which electrons are shared unequally between atoms, due to the unequal distribution of electrons between atoms of different elements. In other words: slightly positive and slightly negative charges appear in different parts of the molecule.
Now, it can be said that a water molecule has a negative side (oxygen) and a positive side (hydrogen). This is how the oxygen atom tends to monopolize more electrons and keeps them away from hydrogen. Thanks to this polarity, water molecules can stick together.