A 2.0-kg block slides down a fixed, rough curved track. The block has a speed of 5.0 m/s after its height above a horizontal surface has decreased by 1.8 m. Assume the block starts from rest. What is the change in mechanical energy of the block caused by the force of friction during this descent?
A. ?14 J
B. ?12 J
C. ?10 J
D. ?16 J
E. ?25 J
Answer: C
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