8.Question 8Isolation mass is another key concept in understanding the formation of planetesimals and eventually planets. We sometimes use the term "oligarch" to describe a body which has become isolated. Which of the following statements about isolation mass is false?1 pointDynamical friction causes the oligarchs to slow each other downOligarchs get more massive futher out in the diskWhen an object reaches isolation mass it stops growing rapidly by gravitational focusingAll of these statements are trueIsolation masses are much higher outside of the ice lineOligarchs are space further and further apart further out in the dis

Which of the following is the best description of the formation of a giant planet with a massive core? (at least as described in the lectures!)1 pointPlanetesimals grow through gravitational focusing. Dynamical friction slows the motions of the largest objects leading to runaway growth of oligarchs, which are isolated from other nearby oligarchs. Gas slowly accretes onto the oligarch through an envelope until the pressures are too high to support the envelope and massive amounts of gas collapse making the gas giant.Planetesimals grow through gravitational focusing. Dynamical friction slows the motions of the largest objects leading to runaway growth of oligarchs, which are isolated from other nearby oligarchs. Large numbers of oligarchs merge over hundreds of millions of years, leading to a giant core.Gas slowly accretes onto the oligarch through an envelope until the pressures are too high to support the envelope and massive amounts of gas collapse making the gas giant.Planetesimals grow through gravitational focusing. Dynamical friction slows the motions of the largest objects leading to runaway growth of oligarchs, which are isolated from other nearby oligarchs. The gravitational pull of the oligarch quickly overcomes the rotational and pressure forces from the disk, causing rapid growth of the gaseous atmosphere.In a massive disk the force of gravity in a patch of the disk overcomes the pressure and rotational forces and the patch quickly collapses into a giant planet. The heavy materials sink to the bottom and form the core.Planetesimals grow through gravitational focusing. Dynamical friction speeds the motions of the largest objects leading to more frequent collisions and runaway growth of oligarchs, which are isolated from other nearby oligarchs. Gas slowly accretes onto the oligarch through an envelope until the pressures are too high to support the envelope and massive amounts of gas collapse making the gas giant.

3.Question 3Which of the following is NOT required for the formation of a large nearly isotropic Oort cloud full of many small bodies, assuming the scenario that we discussed is the dominant mechanism? 1 pointA planet like Jupiter which is massive enough to scatter bodies out of the solar systemPassing stars which perturb the orbits of low perihelion, high semimajor axis objectsA smaller planet like Neptune to scatter icy bodies inward so they can be ejected by a more massive planet like JupiterA population of small bodies which is close enough to a planet to get scattered outwardMultiple stellar encounters to randomize the cometary orbits into an isotropic cloudAll of these are required

5.Question 5The "minimum mass solar nebula" shows how much initial mass was needed in the disk around the sun to form the planets that we know of today. Which statement about the minimum mass solar nebula below is FALSE?1 pointThe minimum mass solar nebula approximately accounts for all of the hydrogen and helium that were present in the initial disk but which were not incorporated into the terrestrial planets.All of these are trueMars appears to have less mass than would be predicted by a smooth minimum mass solar nebula The disk of material around the sun could have had more material than the minimum mass solar nebulaThe initial distribution of mass in the solar system could have been very different from that reconstructed in the "minimum mass solar nebula"

True or false?The Law of Conservation of Mass states:"In an isolated system matter cannot be created nor destroyed"Question 1Select one:TrueFalseQuestion 2Not yet answeredMarked out of 2Flag questionQuestion textWhat is matter?Question 2Select one or more:Matter takes up spaceMatter is always a solidMatter has massMatter cannot be destroyedMatter has a smellMatter can be createdMatter has volumeQuestion 3Not yet answeredMarked out of 1Flag questionQuestion textMatter is only the non-living things around us.Question 3Select one:TrueFalse

Question 3Which of the following is NOT required for the formation of a large nearly isotropic Oort cloud full of many small bodies, assuming the scenario that we discussed is the dominant mechanism? 1 pointA planet like Jupiter which is massive enough to scatter bodies out of the solar systemPassing stars which perturb the orbits of low perihelion, high semimajor axis objectsA smaller planet like Neptune to scatter icy bodies inward so they can be ejected by a more massive planet like JupiterA population of small bodies which is close enough to a planet to get scattered outwardMultiple stellar encounters to randomize the cometary orbits into an isotropic cloudAll of these are required