Large radio telescopes, like the one in Arecibo, Puerto Rico, can detect extremely weak signals. Suppose one radio telescope is sensitive enough to detect a signal which lays down only 0.95 pW of power on an area of 6.1 × 1017 m2. (a) What would be the total power that would be received by the antenna, assuming that its diameter is 380 m? (b) What would be the power of a source at 17000 ly distance from Earth that could provide such a signal? A light-year is the distance light travels in one year.

Sunidhi made a study chart about changes in states of matter. which headings best complete the chart?

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?

Name three populations commonly found in a prairie system