When given a choice, students prefer announced exams over unannounced exams. This information reduces stress because students can relax except on the day that the exam is given. This interpretation of reduced stressed by being able to relax is based on the .
1. preparatory response hypothesis
2. safety hypothesis

2. safety hypothesis                      

Explanation:

Safety hypothesis: In psychology, the term "safety hypothesis" is described as a phenomenon that signifies that arousal is considered as to be greatest for any unpredictable thing that happens in an organism's life during the "intertrial intervals" instead of a presentation of the information. However, it is responsible for reducing or preventing expressions associated with fearful behaviors.

In the question above, the given statement represents the safety hypothesis.

a. formula: f=ma or f/m=a

10,000n/1,267kg≈7.9m/

b. formula: a= and s=d/t

speed= 394.6/15

s=26.3m/s

a=

a=1.75m/

c. 7.9-1.75=difference of 6.15m/

d. the force that most likely caused this difference is friction forces