Suppose we had a laser system with a stimulated emission cross section of 10-16 cm2 and an initial inversion of 1014 cm-3 filling a cavity 50 cm long. the cavity uses mirrors with reflectivities r2 = 0.9 (t2 = 0.1) and rl =0.98 (t1 = 0) and contains a nonsaturable loss of 2% per roundtrip. (a) by what factor is the system above threshold (i. e., what is the ratio of δn/δnt)? (b) estimate how long it would take for the laser intensity to increase (from noise) by a factor of 105. (ignore saturation.)

You notice a very one-dimensional-thinking snail crawling along one rail of a railroad track. naturally, you remove it to a safer place. but before you do, you observe it as it moves from position xi = -92.9 cm to position xf = -64.9 cm along the rail, as measured from a point where one rail abuts the next. what is the snail\'s displacement δx in centimeters?

In which situation has the independent variable for the experiment been changed? check all that apply. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of ph on duckweed growth to testing the effect of light levels on duckweed growth changed from testing the effect of acid ph on duckweed growth to testing the effect of basic ph on duckweed growth

What is the momentum of a 2 kg object moving at 15 meters per second