Question 134: Laws of Motion

Question

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/s
2
)

Accepted Answer

(m
1
g $$-$$ 2T) = m
1
a $$-$$ (1)
T $$-$$ m
2
g = m
2
(2a)
2T $$-$$ 2m
2
g = 4m
2
a $$-$$ (2)
m
1
g $$-$$ 2m
2
g = (m
1
+ 4m
2
) a
a = $${{(8 - 4)g} \over {(8 + 8)}} = {4 \over {16}}g = {g \over 4}$$
a = $${{10} \over 4}$$ m/s
2
S = $${1 \over 2}$$ at
2
$${{0.2 	imes 2 	imes 4} \over {10}}$$ = t
2
t = 0.4 sec

Answer

0.34 s

Answer

0.2 s

Answer

0.25 s

Answer

0.4 s

Laws of Motion

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/s 2 )

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