ASTRO 101 EXAM. QUESTIONS WITH 100% CORRECT ANSWERS.

In this diagram of an accretion disk, there are two particles of dust labeled "A" and "B". A is closer to the black hole, while B is further away. How do their orbital times (time to travel around the black hole) compare? A takes less time to orbit the black hole than B. How does material move inward through the accretion disc? Bits of material collide with each other, losing speed but creating heat that then radiates away. As they lose speed, they fall inward. Imagine two particles of dust, A and B, are inside an accretion disk of a black hole. Particle A is closer to the black hole and particle B is further from the black hole. If they were the same temperature and emitted the same light, how would their colours compare to you as a distant observer? The light from particle A will appear redder, while the light from particle B appears bluer. Which statement describes the effect of gravitational tidal forces? Tides cause the nearer side of an object in orbit to be pulled more forcefully while the far side of the object is pulled more weakly. In this image, an observer watches a spinning accretion disc. One side moves toward him while the other moves away. How do the colors of each side compare? The side moving toward him appears bluer and the side moving away from him appears redder. What strange phenomena occur within the event horizon of a black hole? -Radial distance and time interchange, so we cannot move outward in space similar to how we normally cannot move backward in time. -All light rays end up travelling toward the centre of the black hole, regardless of where they are aimed. Penrose diagram What is the name of this diagram, which plots the structure of a black hole as radius versus time? What effects are caused by the rotation of a black hole? -The event horizon is pulled inwards. Space-time is dragged slightly around the black hole, causing objects to also rotate around the black hole. -The ISCO is pulled inwards. Two particles have the same mass. If particle A has a velocity 2 times higher than particle B, how do their de Broglie wavelengths compare? Particle A has a de Broglie wavelength half that of particle B. If particle A has a velocity 2 times higher than particle B, and half its mass, how do their de Broglie wavelengths compare? Particle A has a de Broglie wavelength equal to that of particle B. Which of the following seems to violate the thermodynamics of entropy? -Heat moving from something cold to something hot. -A broken cup being dropped and coming back together into a functional cup. If we compared the spectrum of a black hole with the spectrum of a blackbody emitter, when both have the same temperature, what difference would we see? We would see no difference in the spectra. How hot would a black hole be if it had the mass of the Moon? -270 degrees celsius - the same temp as space What is likely to happen if the Large Hadron Collider creates a super-tiny black hole? -Such a black hole would evaporate very quickly. -A team of scientists would become famous. -Such a black hole would pose essentially no risk. What are weaknesses in the multi-coloured disc model? -We can't see whether the accretion disc extends all the way to the ISCO. -It is difficult to determine the spin of the black hole, which would affect this model. -The material in the disc is likely a plasma, which will be difficult to model because of magnetic effects.