How did edwin hubble study the redshifting of light from nebulae?

Aknife blade is a(n) a. lever b. screw c. wedge d. inclined plane

Determine the maximum r-value of the polar equation r =3+3 cos 0

Which of these statements is true? a. quarks pair with leptons to form protons and neutrons. b. quarks pair with bosons to form photons. c. quarks pair with photons to form protons and neutrons. d. quarks pair with other quarks to form protons and neutrons. e. quarks pair with electrons to form protons.