Dear Liyuang,

Your score in Exam 2 is  87 out of 100

Everything was right except

#1: You did not explain how you did the
complicated t-integral, Maple?: -3 points

#8: wrong answer, serious error
did dt instead of 
|r'(t)| dt= \sqrt(14) dt: - 6 points

#9: wrong answer, right way except you did not
multiply by -1 (downward diretion)
(even with this it would be the wrong answer): - 4 points


Best wishes,

  Dr. Z.