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PhysicsNLMFrictionMedium2 minQB

PhysicsMediumsingle choice

Passage / Comprehension

The slipping starts between the blocks when the force of 25 N acts on 2kg block.

Acceleration of both the blocks when 40 N force acts on 2 kg block is

Options:

Answer:

Solution:

Since slipping starts at $F = 25 N$ , friction between blocks becomes kinetic when $F = 25 N$ . Before $F = 25 N$ , both blocks move together with the same acceleration.

On drawing a combined F.B.D.:

Thus, when $F = 25 N$ :

$F = 5 a \Rightarrow 25 = 5 a \Rightarrow a = 5 m/ s^{2}$

F.B.D. of 2 kg:

$F - f = 2 a \Rightarrow 25 - f = 2 \times 5 \Rightarrow f = 15 N$

Now, when $F = 40 N$ is applied,

F.B.D. of 2 kg:

$F - f = 2 a_{2} \Rightarrow 40 - 15 = 2 a_{2} \Rightarrow a_{2} = 12.5 m/ s^{2}$

F.B.D. of 3 kg:

$f = 3 a_{3} \Rightarrow 15 = 3 a_{3} \Rightarrow a_{3} = 5 m/ s^{2}$

Option (B) is correct.

Stream:JEESubject:PhysicsTopic:NLMSubtopic:Friction

⏱ 2mℹ️ Source: QB

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