astronomy 1l astronomy lab long beach city college impact cratering la

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Astronomy 1L - Astronomy Lab
Long Beach City College
Impact Cratering Lab
Name:
Please go to the web site: http://janus.astro.umd.edu/astro/impact/ You will use Table 1 to
investigate how size of a body affects a collision with Earth. Using the application on the web
site, complete Table 1, fill in blanks below table, and then answer the questions on the
following pages.
TABLE 1
Rocky asteroid hits Earth (land only) at velocity = 20 km/sec
Projectile
Diameter
Result: what
happens? Where?
Crater
diameter
Energy
released
Quake*** Frequency
Magnitude Once every...
500cm=5m
50 m
500 m
5000m=5km
50 km
500 km
=
* Hiroshima and Nagasaki atomic bombs released energy =
**Largest nuclear weapon released energy
***Largest recorded earthquake, Richter scale = Astronomy 1L - Astronomy Lab
Long Beach City College
1-1. Compare the frequency of impacts.
a) For each factor of 10 in diameter, by approximately what factor does the time for the
next similar impact increase?
b) Offer a hypothesis for these dramatic increases.
1-2. Compare the crater diameters in Table 1. For each factor of 10 in projectile diameter, by
what factor does the crater diameter increase (approximately)?
1-3. For each factor of 10 in projectile diameter, by what approximate factor does the energy
released increase?
1-4. The energy released during an impact is given by the kinetic energy formula
E = ½ mv², where m = projectile's mass and v =
its velocity.
a) Since the velocity is kept constant in Table 1, which variable directly influences the
increase in energy?
b) Think of the projectile as being approximately spherical. Compare the volume of a
sphere 1 meter across to a sphere 10 meters across. (If you forgot the formula for the volume of
the sphere search for it online.)
c) How do you account for the dramatic increase in energy released when the projectile's
diameter is increased by a factor of 10? Astronomy 1L - Astronomy Lab
Long Beach City College
1-5. Scientists have observations that support the hypothesis that the Earth was struck by a 10 km
rocky object 65 million years ago. Re-visit the Solar System Collisions web site and re-examine
the consequence of a collision of this magnitude.
a) How much energy is released?
b) How big is the crater? How does the Chicxulub crater compare? Account for any
differences.
c) Read the article Cosmic Collisions (PDF provided in the module) to investigate the
mass extinction that included the dinosaurs. What happened according to this
hypothesis?
e) Could it happen again? What is the frequency of a collision of this scale?
1-6. Other projectile compositions
Change the projectile composition to ice, leaving the other variables as Earth (land
only), projectile diameter of 500m, and a velocity of 20 km/s.
Projectile
Diameter
Result: what happens?
Where?
500m
Crater Energy
diameter released
Quake*** Frequency
Magnitude Once every…..
a) Comparing with the result in Table 1, which projectile causes a more destructive
impact, rock or ice?
b) Which variable in the kinetic energy formula (from 1-4) has changed? Astronomy 1L - Astronomy Lab
Long Beach City College
1-7. Velocity
Change the projectile velocity to 60 km/s, leaving the other variables as Earth (land
only), projectile diameter of 500m, and projectile composition rock.
Projectile
Diameter
Result: what happens?
Where?
Crater
diameter
Energy
released
Quake*** Frequency
Magnitude Once every...
500m
How has this affected the energy released?
1-8. Other objects in our solar system:
Use the internet (Google) to find out the names of the largest craters on Mercury, Venus, Moon,
and Mars. If the size of the object that made the crater isn't noted online, estimate it using the
Solar System Collisions application from the web site.
Name of crater Size of crater
Possible Size of object | Internet source
Mercury
Venus
Moon
Mars