The table below show factors that affect sleep patterns in humans, with locations of sleep stimulants X and Y missing from the table. Stimulus Internal
or
External Response
Time of day X Lets the body know when it is time to go bed
Levels of chemical serotonin Y Tells the body it is sleepy or encourages alertness

What are X and Y?
A.
X is external; Y is internal

B.
X is internal; Y is external

C.
X and Y are external

D.
X and Y are internal

A250-n box is at rest on a frictionless horizotal floor. then a person shoves the box with a non-zero force of magnitude p. which statement best describes the relationship betweeen p and the motion of the box after it was shoved? -the box will not move when p< 250n but otherwise will accelerate at a constant rate that is directly proportional to p - the box will begin moving at a speed that is directly proportional to p, then will gradually slow to a halt -the box will move with constant velocity at a speed that is directly proportional to p -box will accelerate across the floor at a constant rate that is directly proportional to p

Aparticle moves in the xy plane with constant acceleration. at time zero, the particle is at x = 6 m, y = 8.5 m, and has velocity ~vo = (9 m/s) ˆı + (−2.5 m/s) ˆ . the acceleration is given by ~a = (4.5 m/s 2 ) ˆı + (3 m/s 2 ) ˆ . what is the x component of velocity after 3.5 s? answer in units of m/s.

More solar radiation is absorbed by earth’s surface than by