Welcome back to our lesson on "Forces and Energy."
Today, we will discuss a subset of forces...
called noncontact forces.
These are observed when two objects exert a push or pull on one another at a distance.
Or in the absence of direct contact.
This is in contrast with a contact force, which arises from physical contact between two objects.
In this video, we will explore common types of noncontact forces.
And outline concepts
to help you become more familiar with how they work.
Great so let’s begin!
A noncontact force is the push, or pull...
that an object experiences within a field.
Fields,
like gravitational or electromagnetic field,
will exhibit forces on objects within its space.
Given the magnitude of force
is mass * the acceleration of an object,
where the level of acceleration applied to an object
depends on proximity.
Thus, the forces experienced by an object
in a field...
depend on its mass and its location within the field.
The gravitational force...
is an attractive force that acts between all objects.
In fact,
every particle in the universe exerts attraction on other particles
However...
The gravitational force generated between two masses
is considered an action-reaction pair.
Therefore, you should think of gravitational attraction
as two separate forces of equal intensity...
or magnitudes... but in opposite directions.
To help you understand what affects the magnitude of gravity,
we’ve outlined the high-level concepts of gravitational attraction.
And this illustration...
we’re using the size of the force arrows as a representation of gravitational magnitude.
Like other noncontact forces,
the magnitude of gravitational force is largely dependent on the masses and proximity of both objects in question.
For example,
if one object decreases in mass...
its gravitational field strength diminishes.
And thus...
the gravitational attraction between the two objects
becomes less significant.
In addition, the greater the distance apart...
the less gravitational force is exerted between two masses.
And also note...
the magnitude of the gravitational force
is extremely small for everyday values of masses.
However, for larger bodies...
its effect becomes much more apparent.
For instance...
the earth has a very apparent gravitational field,
and all of the objects near the earth’s surface
experience a strong gravitational force.
Earth’s gravitational force is calculated by...
the objects mass * the acceleration of gravity,
where the acceleration of gravity is 9.8m/(s^2).
When the object is near the surface of the earth
this acceleration is constant.
But as you go further and further into space...
the force diminishes.
The electric force can be attractive or repulsive.
It acts between objects that have an electrical charge.
Where like charges cause a repulsive force...
and unlike charges cause an attractive force.
Furthermore...
the magnitude of the electric force increases with proximity.
Thus, the magnitude of electric force
depends on both the charge of the objects in question...
and their distance apart from each other.
For example...
Two objects that are negatively charged,
and close together...
will create a strong repulsive force.
If one of these charges were positive
there would be a strong attractive force.
The last noncontact force we will cover...
is the magnetic force.
Despite some key differences,
it is similar to the electric force in many ways.
For instance,
an electrified object has a surrounding electric field...
and surrounding a magnet, there is a magnetic field.
And like the electric field...
magnetic fields have both a magnitude
and a direction of acceleration.
Magnetic forces can be attractive or repulsive
These forces are exerted between objects that are magnetized.
Where like poles cause a repulsive force...
and opposite poles cause an attractive force.
Furthermore, the intensity of the magnetic force
increases with proximity.
Thus, the magnitude of the magnetic pull weakens...
as the object gets farther and farther away from the magnet.
This was an overview of common noncontact forces.
We hope that you’ll explore our other educational videos on Forces and Energy.
Thank you for watching.