A spelunker is surveying a cave. She follows a passage 140 m straight west, then 210 m in a direction 45 east of south, and then 280 m at 30 east of north. After a fourth unmeasured displacement, she nds herself back where she started. Determine the magnitude and direction of the fourth displacement.

Sally turns on her cellular telephone to speak to her friend who is located thousands of miles away. which of the following best describes how such a telephone is able to transmit and receive information? a. the cellular telephone transmits, receives, and encodes information using only sound waves. b. the cellular telephone transmits, receives, and encodes information using only electromagnetic waves. c. the cellular telephone transmits information by electromagnetic waves to a receiver which then encodes them and produces sound. d. the cellular telephone transmits information by sound waves to a receiver which then encodes them and produces electromagnetic waves.