Question

question 8 of 10
why is it important to define a frame of reference?
a. an observer cannot be moving.
b. a stationary observer is always moving.
c. motion must be defined relative to something.
d. its impossible to measure motion.

Explanation:

Motion is relative. A frame of reference provides a standard to define and measure motion. Without it, it's unclear how an object is moving. Option A is incorrect as an observer can be moving. Option B is a mis - statement as a stationary observer is considered non - moving in their own frame. Option D is incorrect as motion can be measured relative to a frame of reference.

Answer:

C. Motion must be defined relative to something.