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  4. Referring the graphs, which of the following is/are correct?

Q. Referring the graphs, which of the following is/are correct?Physics Question Image

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Solution:

Option (1) is correct because at 3 , force is opposite to displacement.
At $b, u$ is minimum.
Option (2) is incorrect because at 2 , there is net force and hence no equilibrium.
Option (3) is correct because at 1,3 and $b$ force is zero.
At $b, \frac{d u}{d x}=-F=0$
Option (4) is correct. Positive work is done after position 1.
Hence, $KE$ will increase. So $KE$ is least at 1 .

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