Physical Science, module 16 Flashcards
Define “nuclear fission”.
The process by which a large nucleus is split into two smaller nuclei.
Define “critical mass”.
The amount of an isotope necessary to cause a chain reaction.
Define “star magnitude”.
The brightness of a star on a scale of -8 to +17. The smaller the number, the brighter the star.
Define “light year”.
The distance light travels in one year.
Define “galaxy”.
A massive group of hundreds of millions of stars, all interacting through the gravitational force, orbiting around a common center.
Name the four regions of the sun.
The core, the radiation zone, the convection zone, and the photosphere.
Why would nuclear fusion be a better option for energy production than nuclear fission?
Because there are no radioactive byproducts, there is no chance of meltdown, and the starting materials are cheap.
Why can’t we use nuclear fusion to produce energy?
Because we cannot make it efficient enough to be economically feasible.
What is the main difference between novas, supernovas, and pulsating variables?
Their lifespan.
What is a nebula?
A cloud of bright gases that are the remains of a supernova.
What are the two main methods for measuring the distance from the earth to a star?
The parallax method and the apparent magnitude method.
What are the four types of star groups in the universe, from smallest to biggest?
Galaxies, groups, clusters, superclusters.
Why are Cepheid variables so important for measuring long distances in the universe?
Because they have a relationship between their period and their magnitude. This allows them to be used in the apparent magnitude method.
Define “nuclear fusion”.
The process by which two or more small nuclei fuse to make a bigger nucleus.
