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F4.Physic求解答?
2015-10-21 11:39 am
Blocks A and B are connected by a light inextensible string(of mass 0Kg) and rest on a smooth horizontal table.The masses of A and B are 2kg and3kg respectively. Block A is pulled by a force of 2N.Find the tensions at two wnds X and Y
回答 (1)
2015-10-21 3:55 pm
Where are X and Y?????
Before you give further information on X and Y, the solution below is for calculating the string tension.
Let T be the string tension and a be the acceleration of the blocks.
Apply: net-force = mass x acceleration on block A
2 - T = 2a ----- (1)
For block B:
T = 3a
i.e. a = T/3 ----- (2)
Substitute (2) into (1)
2 - T = 2T/3
solve for T gives T = 6/5 N = 1.2 N
With the given new diagram, tensions on the string at X and Y are the same (= 1.2 N), only that they are in opposite direction (tension at X acts towards the left, whereas tension at Y acts towards the right).
Before you give further information on X and Y, the solution below is for calculating the string tension.
Let T be the string tension and a be the acceleration of the blocks.
Apply: net-force = mass x acceleration on block A
2 - T = 2a ----- (1)
For block B:
T = 3a
i.e. a = T/3 ----- (2)
Substitute (2) into (1)
2 - T = 2T/3
solve for T gives T = 6/5 N = 1.2 N
With the given new diagram, tensions on the string at X and Y are the same (= 1.2 N), only that they are in opposite direction (tension at X acts towards the left, whereas tension at Y acts towards the right).
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