Here's a hypothesis for the duckweed experiment: "if duckweed is grown at pH 5, then it will grow at the same rate as when grown at pH 7, or normal pH, because it can tolerate mildly acidic environments." Which elements should be controlled variables for this experiment?

Check all that apply.

- environmental pH

- ✓ timing of experiment

- duckweed population

- ✓ environmental light

- ✓ amount of nutrients

- ✓ environmental temperature

the answers for whoever needs it :)

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Ateam of astronauts is on a mission to land on and explore a large asteroid. in addition to collecting samples and performing experiments, one of their tasks is to demonstrate the concept of the escape speed by throwing rocks straight up at various initial speeds. with what minimum initial speed vesc will the rocks need to be thrown in order for them never to "fall" back to the asteroid? assume that the asteroid is approximately spherical, with an average density p 3.84 x108 g/m3 and volume v 2.17 x 1012 m3 recall that the universal gravitational constant is g 6.67 x 10-11 n m2/kg2

A200-n force is applied to the foot-operated air pump. the return spring s exerts a 2.6-n·m moment on member oba for this position. determine the corresponding compression force c in the cylinder bd. if the diameter of the piston in the cylinder is 40 mm, estimate the air pressure generated for these conditions. state any assumptions. enter a positive number for the compression force c.

During the past 150 years in the united states, how did energy consumption compare to population growth