The gravitational force between which two objects would be the most difficult to notice?
OA. a water particle and an air particle
OB. the Moon and a water particle
C. the Earth and the Sun
OD. the Moon and the Earth

they are non-matter

explanation:

they are non-matter. basically, any type of energy or any abstract concept is an example of something that does not matter. other examples include dreams, magnetism, radio, and hate

3.2x10^7

no. dot product   =0 when vecs at right angles

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle