Astronomers initially had difficulty identifying the emission lines in quasar spectra at optical wavelengths because

A constellation is that forms a pattern resembling animals, mythological character, or objects

Sue observes a clear plastic, millimeter ruler under low power of her microscope. She sees three divisions of the ruler. What would be the field diameter of Sue's microscope on low power? (in micrometers ('µm')

Light takes 1.28 s to travel from the moon to earth. what is the distance between them?

An nfl linebacker can go from 0 m/s to 2.5 m/s in 2.5s. What is his acceleration?

A projectile is launched with the velocity of 100 meters/second and at an angle 45° from horizontal. If the projectile's hang time is 14.43 seconds, what is its range?

A tree is blown down by wind

You wish to design a system to communicate privately with EM radiation inside your home. The communications should not be visible, and people outside of the walls of your home should not be able to spy on them.

When the power goes off, Jack does not have a flashlight so he uses a glow stick to provide light. He is not very satisfied with how long the glow stick lasts.

Which of the following is a key assumption of the scientific method

A car goes from 80 km/h to 20 km/h in 0.5 h. What is the acceleration in km/h squared?