APHY 101 VERSION ALL FINAL PAPER QUESTIONS AND COMPLETE
SOLUTIONS
⩥ You're orbiting the Earth at 7.8 km/sec in a circular orbit. If you slow
down to 7.7 km/sec, your new orbit will be circular but will be a bit
closer to the Earth. (T/F). Answer: F - In many situations, if you slow
down, you will fall into a lower orbit (but note, if you started in a
circular orbit, the new orbit will be elliptical - that's the first reason the
answer is FALSE here). Also, in this case, you need to remember that
7.8 km/sec is the MINIMUM speed required to be in the lowest possible
Earth orbit. If you slow down a little bit, your new orbit will become an
ellipse with the perigee INSIDE THE EARTH! In other words, your
flight will become suborbital and you will fall to the ground.
⩥ You're in an elliptical orbit around the Earth. At perigee you increase
your speed from 11 km/sec to 12 km/sec. The new orbit will be an
elliptical orbit with a higher apogee. (T/F). Answer: F - In some cases,
speeding up will get you to a larger elliptical orbit with a higher perigee.
But remember that 11.2 km/sec is the Earth's ESCAPE SPEED - beyond
this, the orbit changes shape and becomes hyperbolic. No apogee!
, ⩥ Your spacecraft is heading east in an orbit around the Earth. You want
to get to a higher orbit. To make this maneuver you must first make sure
that your nozzle is facing. Answer: West - Another question that tests
you on multiple concepts. To get to a higher (larger) orbit you know you
must SPEED UP. This means the nozzle must point toward where you
came from (in this case, the west) in order to achieve a speedup when
you fire the engines. Had the nozzle been pointing east, if you fired the
engines you'd SLOW DOWN and drop to a lower orbit.
⩥ When do experience maximum acceleration during a launch?.
Answer: Just before burnout
⩥ The period of the Earth-Mars Hohmann transfer orbit is 16 months. It
is therefore possible to get to Mars by a Hohmann transfer orbit in.
Answer: 8 months
⩥ When you are many millions of kilometers away from any planet,
moon, asteroid, or comet, then you are not in orbit around anything at
all. (T/F). Answer: F - As long as you're within the Solar System, in this
case you'll be orbiting the Sun. Even though the Sun may also be very
far away from your location, it's so massive that its gravitational pull
dominates.
⩥ For most of the journey from Earth to Jupiter, you'll measure your
velocity with respect to. Answer: the center of the Sun
SOLUTIONS
⩥ You're orbiting the Earth at 7.8 km/sec in a circular orbit. If you slow
down to 7.7 km/sec, your new orbit will be circular but will be a bit
closer to the Earth. (T/F). Answer: F - In many situations, if you slow
down, you will fall into a lower orbit (but note, if you started in a
circular orbit, the new orbit will be elliptical - that's the first reason the
answer is FALSE here). Also, in this case, you need to remember that
7.8 km/sec is the MINIMUM speed required to be in the lowest possible
Earth orbit. If you slow down a little bit, your new orbit will become an
ellipse with the perigee INSIDE THE EARTH! In other words, your
flight will become suborbital and you will fall to the ground.
⩥ You're in an elliptical orbit around the Earth. At perigee you increase
your speed from 11 km/sec to 12 km/sec. The new orbit will be an
elliptical orbit with a higher apogee. (T/F). Answer: F - In some cases,
speeding up will get you to a larger elliptical orbit with a higher perigee.
But remember that 11.2 km/sec is the Earth's ESCAPE SPEED - beyond
this, the orbit changes shape and becomes hyperbolic. No apogee!
, ⩥ Your spacecraft is heading east in an orbit around the Earth. You want
to get to a higher orbit. To make this maneuver you must first make sure
that your nozzle is facing. Answer: West - Another question that tests
you on multiple concepts. To get to a higher (larger) orbit you know you
must SPEED UP. This means the nozzle must point toward where you
came from (in this case, the west) in order to achieve a speedup when
you fire the engines. Had the nozzle been pointing east, if you fired the
engines you'd SLOW DOWN and drop to a lower orbit.
⩥ When do experience maximum acceleration during a launch?.
Answer: Just before burnout
⩥ The period of the Earth-Mars Hohmann transfer orbit is 16 months. It
is therefore possible to get to Mars by a Hohmann transfer orbit in.
Answer: 8 months
⩥ When you are many millions of kilometers away from any planet,
moon, asteroid, or comet, then you are not in orbit around anything at
all. (T/F). Answer: F - As long as you're within the Solar System, in this
case you'll be orbiting the Sun. Even though the Sun may also be very
far away from your location, it's so massive that its gravitational pull
dominates.
⩥ For most of the journey from Earth to Jupiter, you'll measure your
velocity with respect to. Answer: the center of the Sun
