In the given constraint, if the string is inextensible and pulley is frictionless, then magnitude of velocity of block A(VA) is
A
10m/s
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B
20m/s
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C
15m/s
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D
5m/s
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Solution
The correct option is B20m/s
Velocity of pulley, VP=VA+VB2 Putting VP=10m/s,VB=0, we get VA=20m/s (upward direction)
Alternative solution:
Since the string is inextensible, therefore Xp+(XP−XA) = length of string ⇒2Xp−XA=L Differentiating w.r.t time, we get equation in terms of velocity i.e. ⇒2Vp−VA=0 ⇒VA=2VP VA=2(10)=20m/s