7. A 2.0-kg block starts from rest on the positive x axis 3.0 m from the origin and thereafter has an acceleration given by
. The torque, relative to the origin, acting on it at the end of 2.0 s is:
(A) (0 N●m)
(B)(-18N●m) ![](https://img.yamol.tw/file/66062aa97bb28.jpg#s-28,38#s-28,38#s-28,38#s-28,38#s-28,38)
(C) (+24 N●m)
(D)(-I44N●m) ![](https://img.yamol.tw/file/66062aa97bb28.jpg#s-28,38#s-28,38#s-28,38#s-28,38#s-28,38)
(E) (+144 N● m)
.