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QJEEM21Ph97d0: JEE Main 2021 Physics - Class 11 JEEM21Ph97d0 Solution: The boxes of masse 2 kg and 8 kg are connected by a massless…

The boxes of masse 2 kg and 8 kg are connected by a massless string passing over smooth pulleys. Calculate the time taken by box of mass 8 kg to strike the ground starting from rest. (use g = 10 m/s2)

JEE Main 2021 (Online) 27th August Evening Shift Physics - Laws of Motion Question 72 English

Multiple Choice Options

  • A 0.34 s
  • B 0.2 s
  • C 0.25 s
  • D 0.4 s

Step-by-Step Verified Solution

JEE Main 2021 (Online) 27th August Evening Shift Physics - Laws of Motion Question 72 English Explanation
(m1g −- 2T) = m1a −- (1)

T −- m2g = m2(2a)

2T −- 2m2g = 4m2 a −- (2)

m1g −- 2m2g = (m1 + 4m2) a

a = (8−4)g(8+8)=416g=g4{{(8 - 4)g} \over {(8 + 8)}} = {4 \over {16}}g = {g \over 4}

a = 104{{10} \over 4} m/s2

S = 12{1 \over 2} at2

0.2×2×410{{0.2 \times 2 \times 4} \over {10}} = t2

t = 0.4 sec

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