The velocity at which 6 kg mass (shown in figure) strikes the ground when it is released from a height of 6 m above the ground is ______ $\mathrm{m} / \mathrm{s}$. Assume pulley is massless and string is light and inextensible (Take $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}$).

JEE Main · 2026 · 06 Apr 2026 · Shift 2 · Work, Power & Energy

The velocity at which 6 kg mass (shown in figure) strikes the ground when it is released from a height of 6 m above the ground is ______

m / s

. Assume pulley is massless and string is light and inextensible (Take

g = 10 m / s^{2}

(A)7.74✓ Correct
(B)7.20
(C)6.55
(D)4.50

Answer: (A)

Solution

The

6 kg

block descends while the

2 kg

block rises with the same speed. Energy conservation for the system gives

(m_{1} - m_{2}) g h = \frac{1}{2} (m_{1} + m_{2}) v^{2}

, so

(6 - 2) (10) (6) = \frac{1}{2} (8) v^{2}

, i.e.

240 = 4 v^{2}

and

v = 60 \approx 7.74 m/s

JEE Main · 2026 · 06 Apr 2026 · Shift 2 · Single correct option

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