Chapter 2: Q74P (page 543)
DATA Supernova! (a) Equation (16.30) can be written as
where c is the speed of light in vacuum. Most objects move much slower than this (v/c is very small), so calculations made with Eq. (16.30) must be done carefully to avoid rounding errors. Use the binomial theorem to show that if v, Eq. (16.30) approximately reduces to. (b) The gas cloud known as the Crab Nebula can be seen with even a small telescope. It is the remnant of a supernova, a cataclysmic explosion of a star. (The explosion was seen on the earth on July 4,1054 C.E.) Its streamers glow with the characteristic red colour of heated hydrogen gas. In a laboratory on the earth, heated hydrogen produces red light with frequencyrole="math" localid="1668146026646" ; the red light received from streamers in the Crab Nebula that are pointed toward the earth has frequencyEstimate the speed with which the outer edges of the Crab Nebula are expanding. Assume that the speed of the centre of the nebula relative to the earth is negligible. (c) Assuming that the expansion speed of the Crab Nebula has been constant since the supernova that produced it, estimate the diameter of the Crab Nebula. Give your answer in meters and in light-years. (d) The angular diameter of the Crab Nebula as seen from the earth is about 5 arc-minutesEstimate the distance (in light-years) to the Crab Nebula, and estimate the year in which the supernova actually, took place.
Short Answer
a) The expression of the frequency of the sound measured by the receiver when v c is b) The speed of gas cloud Crab Nebula is c) The diameter of the supernova in terms of meters is and the diameter of the supernova in light year is 7.6ly d) The distance of the Crab Nebula from the earth is , and the explosion of the supernova actually took place before