JEE MAIN - Physics (2021 - 27th August Evening Shift - No. 2)
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)
_27th_August_Evening_Shift_en_2_1.png)
0.34 s
0.2 s
0.25 s
0.4 s
Explanation
_27th_August_Evening_Shift_en_2_2.png)
(m1g $$-$$ 2T) = m1a $$-$$ (1)
T $$-$$ m2g = m2(2a)
2T $$-$$ 2m2g = 4m2 a $$-$$ (2)
m1g $$-$$ 2m2g = (m1 + 4m2) a
a = $${{(8 - 4)g} \over {(8 + 8)}} = {4 \over {16}}g = {g \over 4}$$
a = $${{10} \over 4}$$ m/s2
S = $${1 \over 2}$$ at2
$${{0.2 \times 2 \times 4} \over {10}}$$ = t2
t = 0.4 sec
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