Sorry I'm so late, but I just took this test and the answer is white (for people who didn't study well ;) )
Answer:
(a) When the resultant force is pointing along east line, the magnitude and direction of the second force is 280 N East
(b) When the resultant force is pointing along west line, the magnitude and direction of the second force is 560 N West
Explanation:
Given;
a force vector points due east,
= 140 N
let the second force = 
let the resultant of the two vectors = F
(a) When the resultant force is pointing along east line
the second force must be pointing due east


(b) When the resultant force is pointing along west line
the second force must be pointing due west and it must have a greater magnitude compared to the first force in order to have a resultant in west line.


The first question has the answer to your problem! I found the answer key!
The phase and amplitude of rhythms in physiology and behavior are generated by circadian oscillators and entrained to the 24 h day by exposure to the light and dark cycle and feedback from the sleep wake cycle.the extent to which the phase and amplitude of multiple rhythms are similarly affected during altered timing of light exposure and the sleep wake cycle has not been fully characterized.