- #1
Hijaz Aslam
- 66
- 1
Q.In the arrangement shown in fig. the ends P and Q of an inextensible string move downwards with uniform speed u. Pulleys A and B are fixed. The mass M moves upwards with a speed.
ANSWER PROVIDED BY MY TEXT
In the diagram ##vcos\theta=u## therefore ##v=u/cos\theta##
HOW I TRIED TO DO THE PROBLEM:
Here both the ##usin\theta## cancel out but the component ##ucos\theta## of both the vectors u add up. Therefore ##2ucos\theta=v## or ##v=2ucos\theta##
But this is a completely different answer regarding the former one, and the latter answer is marked wrong and the former correct. Why can't we add up the vectors like the latter case?
ANSWER PROVIDED BY MY TEXT
In the diagram ##vcos\theta=u## therefore ##v=u/cos\theta##
HOW I TRIED TO DO THE PROBLEM:
Here both the ##usin\theta## cancel out but the component ##ucos\theta## of both the vectors u add up. Therefore ##2ucos\theta=v## or ##v=2ucos\theta##
But this is a completely different answer regarding the former one, and the latter answer is marked wrong and the former correct. Why can't we add up the vectors like the latter case?
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