What is the primary reason that astronomers put telescopes and other instruments above earth's atmosphere?

the instruments can better view the universe without the distraction of electromagnetic rays emitted by the earth.

the instruments can get closer to the objects they are observing at the extreme ends of the universe.

the atmosphere blocks or absorbs uv, gamma, and x-rays emitted by processes taking place in the universe.

the atmosphere absorbs the infrared light coming in from the sun.

Does heating a metal wire increase or decrease its electrical resistance? why?

Consider a file currently consisting of 200 blocks. assume that the file control block (and the index block in the case of indexed allocation) is already in memory. calculate how many disk i/o operations are required for contiguous, linked, and indexed (single-level) allocation strategies, for each of the conditions listed below. in the contiguous-allocation case, assume that there is not room to grow at the beginning but there is room to grow at the end. also assume that the block information to be added is stored in memory.

If a hiker that weighs 600 newtons climbs a 50 meter hill, how much gravitational potential energy has the hiker gained?