Which of the following is the correct si unit to use in measuring the mass of a boulder
a. ounces
b. tons
c. kilograms
d. pounds
(i'm sorry if i didn't pick the right subject )

The earth remains in orbit around the sun due to the force of gravity. how does the force of gravity exerted by the sun on the earth compare to the force of gravity exerted by the earth on the sun?

An ideal polarizer with its transmission axis rotated 30 degrees to the vertical is placed in a beam of unpolarized light of intensity 10w/m^2. after passing through the polarizer, what is the intensity of the beam? a. 8.7 w/m^2 b. 7.5 w/m^2 c. 5.0 w/m^2 d. 10 w/m^2 e. 2.5 w/m^2

What are similarities and differences between refraction, reflection, diffraction and absorption?