Download The Effects of Gravity

The Effects of Gravity
Identify the source of
gravitational forces and fields
 Identify the source of
gravitational forces and
fields.
 Identify the strongest
gravitational force that you
personally experience.
 Use your mass to calculate
the gravitational force that
you experience each day.
Fg = m x 10N / 1 kg
 Gravitational fields can be
represented by arrows
pointing down towards the
center of a mass.
 Sketch the gravitational
fields that exist between
you and the earth.
Gravity on a Star
 A star has an enormous mass.
This causes it to also have an
enormous Fg. Identify what
happens when you exert a
force over an area.
 The pressure from the star’s
Fg causes the particles in the
star to compress and
undergo nuclear fusion.
 The energy from this fusion
is released as light and also
balances the inward pressure
from the star’s Fg.
 Explain what should happen
if the star produces massive
amounts of energy.
 Explain what would happen
if the star produces a
smaller amount of energy.
Gravity on a Star
 A “young” star fuses
hydrogen into deuterium
and deuterium into helium.
These stars appear yellow,
like our sun.
 As a star runs out of
hydrogen it can become a
red or orange giant, such as
Betelgeuse or Arcturus.
 A star with a helium core
can begin to fuse helium
into carbon. These stars
are white dwarf stars.
They balance the Fg by
having e- repel each other.
 Our sun will end at this
point. Explain what should
happen to a star with a
larger mass than our sun.
Comparing Stars
 Describe the differences in size you see between the sun and
other stars.
Gravity on Larger Stars
 A more massive star has a
greater Fg, so the star
continues to collapse,
fusing carbon into iron,
then crushing electrons into
protons to create neutrons.
 These neutron stars are
also called “pulsars”
because they release light
energy as radio waves,
sending “mysterious”
signals.
 Identify the colors you
expect to see from an iron
core star or a neutron star.
 Explain how you would
demonstrate that radio
waves were emitted by a
star.
Gravity on the Largest Stars
 If a star has even more mass,
the magnitude of its Fg is so
large that it continues to
collapse from a neutron star and
either tears itself apart in a
supernova or completes its
gravitational collapse into a
black hole.
 The equation to determine if a
star is large enough to become a
black hole is Kip Thorne’s Hoop
Conjecture:
C = 2π x mass x (1.48 x 10-27 m/kg)
 Determine the
circumference you would
have to compress to in order
to become a black hole.
 Our sun would become a
black hole if its
circumference becomes 18
km. Determine its mass.
Gravity on the Largest Stars
 Describe some of the
phenomena that take place
around a black hole. These
can be ideas you have heard
about, seen, or read about.
 Explain why it might be
difficult to make careful
observation of black holes.
 Explain what you think
ultimately happens to black
holes.
 Black holes are “black” and
do not shine like stars.
Suggest how scientists
might be able to identify
black holes in the universe.