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Three masses \mathrm{\mathrm{M}=100 \mathrm{~kg}, \mathrm{~m}_{1}=10 \mathrm{~kg}} and \mathrm{\mathrm{m}_{2}=20 \mathrm{~kg}} are arranged in a system as shown in figure. All the surfaces are frictionless and strings are inextensible and weightless. The pulleys are also weightless and frictionless. A force \mathrm{F} is applied on the system so that the mass \mathrm{\mathrm{m}_{2}} moves upward with an acceleration of 2 \mathrm{~ms}^{-2}. The value of \mathrm{F} is : \mathrm{\left(\text { Take } \mathrm{g}=10 \mathrm{~ms}^{-2}\right)}

Option: 1

\mathrm{3360 \mathrm{~N}}


Option: 2

\mathrm{3380 \mathrm{~N}}


Option: 3

\mathrm{3120 \mathrm{~N}}


Option: 4

\mathrm{3240 \mathrm{~N}}


Answers (1)

best_answer

\mathrm{f\rightarrow} Pseudo force on \mathrm{m_{1}} in the frame of block of mass \mathrm{M}

\mathrm{f=m_{1}a}\rightarrow (1)

Let the acceleration of system and block of mass \mathrm{m_{1}}  be \mathrm{a} and \mathrm{a_{1}} respectively

\mathrm{f-T=m_{1}a_{1}}\rightarrow (2)

\mathrm{T-m_{2}g=m_{2}a_{2}}\rightarrow (3)

Common acceleration \mathrm{=a=\frac{F}{m_{1}+m_{2}+m}}

\mathrm{a=\frac{F}{130}}\rightarrow (4)

from eqn 1,2 & 4

\mathrm{\frac{F}{13}-T=10a_{1},=10(2)=20}

\mathrm{(a_{1}=2m/s^{2})}----\mathrm{(Given)}

\mathrm{T-200=20(2)}

\mathrm{T=240}

\mathrm{\frac{F}{13}-240=20}

\mathrm{F=260\times 13}

\mathrm{F=3380N}

Hence (2) is correct option

Posted by

Ritika Kankaria

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