1. the space between stars in a galaxy is millions of times larger than the size of the stars themselves. thus galaxies are mostly 'empty' space. why do galaxies not look like mostly empty space when we see pictures of them? give at least two different reasons.
2. give five pieces of observational evidence supporting the big bang. be able to explain them in your own words.
3. explain where the cosmic microwave background radiation came from.

Aregular polygon has angkes of size 150° each.how many side has the polygon

The frequency of vibrations of a vibrating violin string is given by f = 1 2l t ρ where l is the length of the string, t is its tension, and ρ is its linear density.† (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and ρ are constant) (ii) the tension (when l and ρ are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is ⇒ f is ⇒ (ii) when the tension is increased by turning a tuning peg df dt 0 and t is ⇒ f is ⇒ (iii) when the linear density is increased by switching to another string df dρ 0 and ρ is ⇒ f is ⇒

What is the rate of 12 liters of water moving through a water hose in 4.0 minutes?