Two blocks X and Y of masses 1kg and 2kg respectively are suspended from the ceiling by two light strings P and S.
(i) Find the tension in string S and string P.
(b)If string S suddenly breaks, find
(i)the net force acting on each block, and
(ii)the tension in string P.
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F.4 physics 高手入
2008-11-28 12:17 am
回答 (2)
2008-11-28 12:56 am
✔ 最佳答案
(i) S: 30NP : 20N
(b)If string S suddenly breaks,
(i) X: 10N
Y : 20N
(ii) 0N
參考: my knowledge
2008-11-30 1:02 am
When you solve this questions, you should draw the free body diagrams.
As the system is in equilibrium, so that ↑F = ↓F.
(a)
Firstly, consider X:
Ts = Wx + Tp --------- (1)
Secondly, consider Y:
Tp = Wy ---------(2)
By solving,
Tp = Wy
Tp = my(g)
Tp = 20N
Sub (2) into (1),
Ts = Wx + Tp
Ts = mx(g) + Tp
Ts = (1)(10) + 20
Ts = 30N
(b)(i)
If string S suddenly breaks, you shouldn't consider about anything, just draw the free body diagram and you may see this question is easily to find the answers.
Consider X,
By Newton's second law, F=ma
Wx + Tp = ma
(1)(10) + Tp = ma
10 + 20 = (1)a
a = 30 ms^-2
The net force acting on block X = 30N
The net force acting on block Y = 0N
(ii)
Consider Y:
Tp = Wy
Tp = my(g)
Tp = 20N
As the system is in equilibrium, so that ↑F = ↓F.
(a)
Firstly, consider X:
Ts = Wx + Tp --------- (1)
Secondly, consider Y:
Tp = Wy ---------(2)
By solving,
Tp = Wy
Tp = my(g)
Tp = 20N
Sub (2) into (1),
Ts = Wx + Tp
Ts = mx(g) + Tp
Ts = (1)(10) + 20
Ts = 30N
(b)(i)
If string S suddenly breaks, you shouldn't consider about anything, just draw the free body diagram and you may see this question is easily to find the answers.
Consider X,
By Newton's second law, F=ma
Wx + Tp = ma
(1)(10) + Tp = ma
10 + 20 = (1)a
a = 30 ms^-2
The net force acting on block X = 30N
The net force acting on block Y = 0N
(ii)
Consider Y:
Tp = Wy
Tp = my(g)
Tp = 20N
參考: My Physics and Maths knowledge
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