6.A 3.0-kg mass is projected down a rough, circular track (radius = 2.0 m) as shown. The speed of the mass at point A is 4.0 m/s, and at point B, it is 7.0 m/s. What is the change in mechanical energy
done on the system between A and B by the force of friction?

(A) -24 J
(B) -9.3 J
(C) -8.1 J
(D) -7.2 J
(E) -6.6 J
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統計: A(1), B(17), C(0), D(2), E(0) #3081246
統計: A(1), B(17), C(0), D(2), E(0) #3081246