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4-1.Newton's Laws of Motion
medium
A block of mass $2\, kg$ is suspended $5\,m$ from a string, is released from a height of $5\,m$ as shown in figure then what will be the impulse when string. Just becomes tight ............ $N-s$
A
$2$
B
$0.2$
C
$20$
D
$200$
Solution
Velocity acquired by the block when it reaches to
lowest position $=\sqrt{2 \mathrm{gh}}$
$\mathrm{V}_{\mathrm{i}}=\sqrt{2 \times 10 \times 5}=10 \mathrm{m} / \mathrm{s}$
Velocity when string becomes fight $V_{f}=0$
$\mathrm{I}=\mathrm{m}\left(\mathrm{V}_{f}-\mathrm{V}_{i}\right)=2(0-10)=20 \mathrm{N}-\mathrm{S}$
Standard 11
Physics
