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Give answer! - Laws of motion - JEE Main-2

A body of mass 2 kg slides down with anacceleration of 3 m/{s^{2}} on a rough inclined plane having a slope of 30^0. The external force required to take the same body up the plane with the same acceleration will be : (g=10 m/{s^{2}})

  • Option 1)

    14N

  • Option 2)

    20N

  • Option 3)

    6N

  • Option 4)

    4N

 
Answers (2)
106 Views
N neha
V Vakul

As we have learnt

Retardation of block sliding up over a rough Inclined plane -

ma=mg\ sin\theta+F

ma=mg\ sin\theta+\mu mg\ cos\theta

ma=g[sin\theta+\mu cos\theta]

- wherein

For \mu=0

a =g\left ( sin\Theta -\mu cos\Theta \right )\rightarrow (1)

To move body up with same accelaration

F-\left ( \mu\: mg\: cos\Theta +mg\: sin\Theta \right ) =m\left ( g\: sin\Theta -\mu\: g\: cos\Theta \right )

F=2.m\: g\: sin\Theta

F=20N


Option 1)

14N

Option 2)

20N

Option 3)

6N

Option 4)

4N

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