5. A sled loaded with sand, slides along a horizontal frictionless track. As the
sled moves, sand trickles out at a constant mass-reduced rate through a hole in
the back. The speed of the sled will:
(A) decrease at a constant rate
(B)
increase at a constant rate
(C) remain the same
(D) decrease at a variable rate
(E) increase at a variable rate.
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統計: A(0), B(0), C(0), D(0), E(1) #3332064
統計: A(0), B(0), C(0), D(0), E(1) #3332064
詳解 (共 2 筆)
#7395708
那這題需多人看到這題會先想到動量公式
質量減少,動量不變,所以速度會變快
但是因為其在水平面而且不受到多餘的外力
所以水平速度不變
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