Which of the following is not an example of accelerated motion?
a. an airplane taking off down a straight runway
b. a boulder falling off a cliff in a straight path
c. a ball being thrown straight up
d. a bicyclist moving in a straight line at a constant speed

Accelerated motion  =  any change in speed or direction.

A.  No.  The airplane's speed is increasing.

B.  No.  The boulder's speed increases as it falls.

C.  No.  The speed of the ball decreases as it approaches the peak,
then it changes direction, begins to move downward, and its speed
increases steadily after that.

D.  Yes.  The cyclist's speed and direction are not changing.

Iwould sure like to answer your question but i honestly just don’t know

The duration of a photographic flash is related to an rc time constantly