Pulley and spring are massless and friction is absent everwhere. 5, kg block is released

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5.Work, Energy, Power and Collision

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Pulley and spring are massless and the friction is absent everwhere. $5\, kg$ block is released from rest. The speed of $5\, kg$ block when $2\, kg$ block leaves the contact with ground is (take force constant of the spring $K = 40\, N/m$ and $g = 10\, m/s^2)$

A

$\sqrt 2\,m/s$

B

$2 \sqrt 2\,m/ s$

C

$2\, m/s$

D

$4 \sqrt 2\,m/ s$

Solution

$\mathrm{kx}=2 \mathrm{g} \Rightarrow \mathrm{x}=0.5$

By $COME$ $5 \times 10 \times 0.5=\frac{1}{2} \times 5 \mathrm{v}^{2}+\frac{1}{2} \times 40 \times(5)^{2}$

$25=\frac{5}{2} v^{2}+5$

$\mathrm{v}^{2}=8$

$\mathrm{v}=2 \sqrt{2} \mathrm{m} / \mathrm{s}$

Standard 11

Physics

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