Two Spaceships Are Traveling Past Earth at 90% of the Speed

question 142

Multiple Choice

Two spaceships are traveling past Earth at 90% of the speed of light in opposite directions (i.e., they are approaching each other) . One spaceship turns on a searchlight, which is seen by scientists aboard the other. What speed do the scientists measure for this light (c = speed of light in a vacuum) ?

• A) 1.9 c (equal to c + 0.9 c)
• B) 1.8 c (equal to 2 *0.9 c).
• C) c
• D) 0.9 c

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Definitions:

Trichromatic Theory

A theory of color vision proposing that the human eye has three types of receptors with different sensitivities to light wavelengths, responsible for the perception of color.

Afterimage Phenomenon

A visual illusion where an image continues to appear briefly even after exposure to the actual image has ceased.

Decibels

A unit of measurement for the intensity of sound, indicating the level of sound pressure or power on a logarithmic scale.

Additive Mixing

A color mixing process in which different colors are created by combining various intensities of light colors, typically red, green, and blue.