23. In the class demonstration, when viewed through the diffraction gratings, the tubes of gas excited by a high voltage source emitted

Explain why a scientific theory can never be proven. If that is true, are scientific theories no better than guesses?

3. Retrograde motion is something that was observed to happen to the planets motion through the sky.      a) What is retrograde motion of the planets?      b) How did Ptolemy try to explain retrograde motion?      c) How does Copernicus’s model explain retrograde motion?

22. An electron emits a ______ when it transitions from a higher energy level to a lower energy level in an atom?

28. Adaptive optics are used to correct which of the following problems?

An airplane flies at an altitude of 6  miles towards a point directly over an observer. Consider  and  as shown in the following figure. The speed of the plane is400 miles per hour. Find  when  miles. Round your answer to three decimal places. ​ ​

Assume that  x  and  y  are both differentiable functions of  t  . Find  when  and  for the equation. ​

Find the points at which the graph of the equation has a vertical or horizontal tangent line. ​ ​

An airplane is flying in still air with an airspeed of 283  miles per hour. If it is climbing at an angle of 21 °, find the rate at which it is gaining altitude. Round your answer to four decimal places. ​

All edges of a cube are expanding at a rate of 7  centimeters per second. How fast is the volume changing when each edge is 2  centimeters? ​