Compare the spectra of mercury and sodium with the spectrum of an interstellar nebula. Most street lights are made from one of two elements—mercury or sodium. Explain why astronomers prefer that cities use sodium street lights instead of mercury street lights.

the focus of lesson 1 is newton's first law of motion - sometimes referred to as the law of inertia. newton's first law of motion is often stated as. an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

explanation:

c.the charges if the proton and electron and gravity

v 154.9= 0.9 length length s little over 154.9cm