Why is there a lower end to the main sequence?
What will be an ideal response?
The mass-luminosity relation tells you why the main sequence must have a lower end. Low-mass objects have lower pressures and temperatures in their cores, and those with less than about 0.08 solar mass are too cool to allow hydrogen fusion.
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What is the primary factor in determining the classification for an elliptical galaxy?
a. size b. shape c. mass d. color
From the center outward, which of the following lists the "layers" of the Sun in the correct order?
A) core, radiation zone, convection zone, photosphere, chromosphere, corona B) core, radiation zone, convection zone, corona, chromosphere, photosphere C) core, convection zone, radiation zone, corona, chromosphere, photosphere D) core, corona, radiation zone, convection zone, photosphere, chromosphere
Suppose that an object is moving with constant nonzero acceleration. Which of the following is an accurate statement concerning its motion?
A) In equal times its speed changes by equal amounts. B) In equal times its velocity changes by equal amounts. C) In equal times it moves equal distances. D) A graph of its position as a function of time has a constant slope. E) A graph of its velocity as a function of time is a horizontal line.
A rod of 2.0-m length and a square (2.0 mm × 2.0 mm) cross section is made of a material with a resistivity of 6.0 × 10^?8 ? / m. If a potential difference of 0.50 V is placed across the ends of the rod, at what rate is heat generated in the rod?
a. 3.0 W b. 5.3 W c. 8.3 W d. 1.3 W e. 17 W