Why did the wright brothers construct their own wind tunnel?

What two observable properties of a cepheid variable are directly related to one another?

Which of the following elements is the most reactive? Beryllium Calcium Magnesium Barium

Three pendulums all have the same length and start from the same height. The first pendulum is very light and has a mass of 67 g. The second pendulum has a mass of 1.5 kg. The final pendulum has a mass of 3.3 kg.

A ball is rolled uphill a distance of 5 m before it slows, stops, and begins to roll back. The ball rolls downhill 9 m before coming to rest against a tree. What is the magnitude of the balls displacement? A. 4 meters B. 9 meters C. 14 meters D.

Which of the following descibes the refraction of a wave?

Three light bulbs are wired in series. What happens if one of these light bulbs burn out

How do you distinguish a pure substance from a mixture?

Does the size of the particles change as the substance changes state?

What is the Z number of an atom with 9 protons, 8 neutrons, and 7 electrons? 7 8 9 16 17

What is the most dense crust