Download Mass vs. Weight and Gravity

Mass vs. Weight
and Gravity
NO BELL WORK TODAY!
Success Criteria:
I can identify gravity.
I can identify mass.
I can identify how mass and distance affect
gravitational pull.
TOC:
#35. Mass vs. weight and
Gravity notes
Mass vs. Weight? (video)

Mass is how much matter is in an object.

Weight is the measurement of the gravitational
force.

Mass is a physical property of all matter that exists
in the universe. It is commonly measured in
kilograms. Regardless of where an object is
located, the mass of the object at any given time
remains the same

. For example, if a person had a mass of 45 kg
on the surface of the Earth, that person’s mass
would also be 45 kg on the moon, or even in
outer space.

Unlike mass, the weight of an object can
change based on where the object is located.
Weight is the amount of gravitational pull on an
object. It is commonly measured in newtons or
pounds. So depending on where an object is,
the gravitational force acting on it could be
different and, accordingly, its weight could be
different.

Since the gravitational force acting on an
object is proportional to its mass, the weight of
an object is proportional to its mass as well.
Gravity in the Solar System

The universal law of gravitation states that every object
with mass exerts a gravitational force on every other
object with mass in the universe.

Gravity plays a vital role in the formation and
movement of the planets, stars, and solar systems.
Stars, planets, galaxies, and galaxy clusters are all
formed and held together by gravity.

Gravity is a force among all objects in the universe.
Within our solar system, every object is attracted to
every other object due to gravity. The closer objects
are and the more mass they have, the stronger the
attraction. Variations in gravitational forces among
objects in the solar system cause variations in the
objects’ orbital speeds.
Mass vs. Gravity

The greater the total mass of two objects is, the greater the
gravitational force between them. For example, a
meteoroid positioned halfway between two asteroids will be
attracted more to the asteroid with greater mass.

The difference in mass between two objects can also affect
how gravity affects the objects’ motion. The motion of the
less massive object is more affected by the force than is the
motion of the more massive object. For example, the planet
Jupiter is much more massive than its moons. This is why
each of its moons orbit around the planet. The gravitational
force between Jupiter and its moons does affect the motion
of Jupiter, but only slightly.

Another example of this is the orbits of all the planets around
the Sun. The Sun is the most massive object in the solar
system. This causes all the planet-moon systems, asteroids,
meteoroids, and comets to orbit around the Sun. The Sun
moves only slightly due to the gravitational force between it
and the planets. Because of this, the Sun stays in the central
part of the solar system while the planets move in large
orbits around it.
Distance & Gravity

The shorter the distance between two
objects, the stronger the gravitational
force between them. For example,
because the Moon’s orbit is elliptical, the
gravitational force between the Earth and
the Moon is stronger when the Moon is
closer to the Earth. When the Moon is
farther away in its orbit, the gravitational
force between it and the Earth is weaker.
Distance & Mass

Both distance and mass influence the
gravitational force between two objects at
the same time. Differences in distance
have a greater effect on gravity than do
the differences in mass. For example, the
gravitational force between the Earth and
Moon is stronger than the force between
the Earth and the Sun. Even though the
Sun has such a great mass, the shorter
distance between the Earth and the Moon
makes the force between the Earth and
Moon much stronger than the force
between the Earth and the Sun.
Gravity & Motion

The Sun contains most of the mass in the solar system.
Accordingly, the Sun exerts a very strong gravitational
force on the other objects in the solar system. Over
time, many objects, including the planets, have
settled into stable orbits around the Sun.

Each moon in the Solar System orbits a planet and
also orbits the Sun. As a moon orbits its planet, the
planet moves around the Sun. So a moon orbits the
Sun at the same time as it orbits its planet.

The sun is the only object in the Solar System that is
essentially stationary relative to the Solar System as a
whole. As the Sun slowly orbits the center of the
galaxy, the entire Solar System comes along with it.
So, relative to the planets, moons, asteroids, and
comets of the Solar System, the Sun does not move.

The gravitational force between a planet and the
Sun, along with the planet’s inertia (continued
forward motion), keeps the planet moving in orbit
around the Sun. Without the Sun’s gravity, a
planet’s inertia would send it traveling in a
straight line off into space. Without a planet’s
inertia, the Sun’s gravity would pull the planet
straight toward it, and the two would collide.

Each planet’s orbit is shaped like an ellipse, which
is nearly circular. This gravitational force also
determines the planet’s orbital speed. The
gravity between planets and the Sun is stronger
for planets closer to the Sun than for planets
farther away from the Sun. The stronger the force
the faster the orbital speed.
Gravity and the Theory of Relativity
F.Y.I. -Einstein theorized that mass warps
(bends/curves) space and this warping explains the
force we call gravity.
Link: How Gravity Really Works (1 min 45 sec)
SPI 0807.12.5
Gravity-Mass and Distance
1) What is the name of the law about gravity? The law of…
A) …Conservation of Mass or B) …Universal Gravitation
(2) All matter in the universe attracts other matter by?
A) A “pushing force” or B) A “pulling force”
(3) The strength of gravity depends on the ______ of the objects
A) Masses or B) Shape
4) Effect of gravity depends on the _____ between the objects.
A) Energy or B) Distance
5) What did Einstein say about mass and gravity?
A) That mass warps space or B) Mass and gravity are the same
SPI 0807.12.5
Gravity-Mass and Distance
Here is an example of a question you might see on a quiz or test.
SPI 0807.12.5
Gravity-Mass and Distance
Here is an example of a question you might see on a quiz or test.
SPI 0807.12.5
Gravity-Mass and Distance
Here is an example of a question you might see on a quiz or test.
SPI 0807.12.5
Gravity-Mass and Distance
Here is an example of a question you might see on a quiz or test.
SPI 0807.12.5
Gravity-Mass and Distance
Here is an example of a question you might see on a quiz or test.
Exit Ticket

True or false

The greater the mass, the greater the
gravitational force.