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Initially elongation in spring is 5 cm a...

Initially elongation in spring is 5 cm and blocks are at rest. An external forece F acting on upper block and it varies with times as F=5t Newton force of firction acting on 10 kg block by ground is `vec(f_(1)` and force of friction on 5 kg block by 10 kg block is `vec(f_(2)`

A

At t=0, `vecF_(1)=50hat(i),vecf_(2)`=0

B

At t=2 sec ,`vecf_(1)= 50 hat(i), vecf_(2)=-10hat(i)`

C

At t= 4sec. `vecf_(1)=30hat(i),vecf_(2)=-20hat(i)`

D

At t= 5sec both blocks start movingt in + ive x-direction

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The correct Answer is:
A, C
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