9th sum

Asked by lovemaan5500 | 23rd Jan, 2019, 08:19: PM

Expert Answer:

top portion of figure gives the free body diagram of both the blocks when force is applied on 10-gram block to hold it.
 
Tension in the string = 0.03×9.8 = 0.294 N ;
 
required force to hold the 10-gram block, F = 0.03×9.8 - 0.01×9.8 = 0.02×9.8 = 0.196 N
 
Free body diagrams of both the blocks are given in the bottom portion of figure. 
10-gram block is moving upwards with acceleration a m/s2 .
30-gram block is moving downwards with acceleration a m/s2
 
at 10-gm block,  T+0.01a = 0.01g  ...........(1)
at 30-gm block,  T-0.03a = 0.03g  .............(2)
 
By subtracting (2) from (1), we get a = - g/2 = -4.9 m/s2 ( -ve sign indicates acceleration is downwards)
by substituting a in eqn.(1), we get T = 0.147 N

Answered by Thiyagarajan K | 23rd Jan, 2019, 11:38: PM

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