更新1:
the answer is 4n
dynamic f6
2010-10-26 2:44 am
Two bodies P and Q are connected by a light string A. The weights of P and Q are 4 N and 10 N respectively. P is connected to the roof by another light string B. If string B is cut and the bodies allowed to fall, the net force acting on P during free fall is
回答 (3)
2010-10-26 3:50 am
✔ 最佳答案
When both P and Q are under free fall, they have the same acceleration and speed. There will not be any relative motion between them. Hence, it is obvious that the tension in the string connecting them is zero. The only force that acts on P is thus its only weight, i.e. 4 N.
2010-10-26 3:29 am
ok la!~~~~~~~
2010-10-25 19:29:50 補充：
give u la!~~~~~~~
2010-10-25 19:40:23 補充：
answer it..
2010-10-25 19:29:50 補充：
give u la!~~~~~~~
2010-10-25 19:40:23 補充：
answer it..
2010-10-26 3:27 am
That means the answer need the momentum net Force of P.
you can determine that when B is cut, A is still equillibium by the B before,
then tension by A will be 0 at this moment,
As B is cut, it's not equillibium for the weight of P,
Then, the only resultant Net force is the weight of P, which is 4N
you can determine that when B is cut, A is still equillibium by the B before,
then tension by A will be 0 at this moment,
As B is cut, it's not equillibium for the weight of P,
Then, the only resultant Net force is the weight of P, which is 4N
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