Aplanet is in an elliptical orbit around a distant star. at periastron (the point of closest approach to the star), the planet is rp=4.50×108 km from the star and is moving with a speed of vp=18.5 km/s . when the planet is at apastron (the point of greatest distance from the star), it is ra=9.10×108 km from the star. how fast is the planet moving at apastron? va=? km/s

Matter that emits no light at any wavelength is called

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.

Awaiver with a period of 0.008 second has a frequency of a. 800hz. b. 80hz. c. 125hz. d. 12.5hz.