The angle a vector makes with the x-axis of a coordinate system must be what size in order to make one or more of its components negative? a)less than 30 degrees b)between 30 and 60 degrees c)between 61 and 90 degrees d)greater than 90 degrees

The sun generates both mechanical and electromagnetic waves. which statement about those wave is true?

Assume similar data for the motion of the blood in your aorta. estimate how many beats of the heart it will take the blood to get from your heart to your brain. (assume that the distance from your heart to your brain is 30 cm)

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.