posted by Drew .
light travells in a straight line at a constant speed of 300,000 km/sec. what is the light's acceleration?
the key word is "constant." a=(v2-v1)/t. The final and initial velocity is equal. What does that do to the acceleration if I do not increase or decrease in speed? Plug it into the equation and let's see... a=(300,000km/sec-300,000km/sec)/time