Are there good quality headphones (both ears) that work with cellphone, computer and iPod?

I’d like to have *one* headset/headphones. I don’t mind if they’re over the head, around the head, with a boom, whatever, as long as they sound good and work for everything, even if they require an adapter.

Everything means:
Cellphone 2.5mm
iPod (standard headphone jack)
Computer (standard headphone jack + standard mic jack) OR USB

OR all bluetooth.

Thanks!

satelite in circular orbit?

A satellite moves in a circle in the earth’s equatorial plane. The satellite is at such a height above the surface of the earth that it appears stationary or not moving (such an
orbit is called geosynchronous).

a. Find the altitude or height of this satellite above the surface of the earth.

b. Explain with a sketch why the radio signals from these satellites cannot directly
reach receivers on earth that are north or south of specific latitude.