The sky, which was bright blue, is now dark. you look up expecting to see a halo of light in the sky. what just occurred?
(a. an aurora
(b. a solar eclipse
(c. a solar black out
(d. a lunar eclipse

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

Aperson stands on a platform, initially at rest, that can rotate freely without friction. the moment of inertia of the person plus the platform is ip. the person holds a spinning bicycle wheel with its axis horizontal. the wheel has moment of inertia iw and angular velocity ωw. take the ωw direction counterclockwise when viewed from above. part a what will be the angular velocity ωp of the platform if the person moves the axis of the wheel so that it points vertically upward?

Consider a hydrogen atom in the ground state. what is the energy of its electron? =e= jj now consider an excited‑state hydrogen atom. what is the energy of the electron in the =5n=5 level? =e5= j