SATHEE: Laws of Motion 3 Question 24

Laws of Motion 3 Question 24

26. In the figure, the blocks $A, B$ and $C$ have masses $3 k g, 4 k g$ and $8 k g$ respectively. The coefficient of sliding friction between any two surfaces is $0.25 . A$ is held at rest by a massless rigid rod fixed to the wall, while $B$ and $C$ are connected by a light flexible cord passing around a fixed frictionless pulley. Find the force $F$ necessary to drag $C$ along the horizontal surface to the left at a constant speed. Assume that the arrangement shown in the figure. i.e. $B$ on $C$ and $A$ on $B$ , is maintained throughout.(Take $g = 10 m / s^{2}$ ).

(1978)

Integer Answer Type Question

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Answer:

Correct Answer: 26. $80 N$

Solution:

Maximum friction between $A$ and $B = μ m_{A} g$

$f_{1} = 0.25 (3) (10) = 7.5 N$

Maximum friction between $B$ and $C = μ (m_{A} + m_{B}) g$

$\begin{aligned} f_{2} & = 0.25 (3 + 4) (10) \\ = 17.5 N \end{aligned}$

Maximum friction between $C$ and ground

$\begin{aligned} f_{3} & = μ (m_{A} + m_{B} + m_{C}) g \\ = 0.25 (3 + 4 + 8) (10) \\ = 37.5 N \end{aligned}$

Block $C$ and hence block $B$ are moving in opposite directions with constant velocities and block $A$ is at rest. Hence, net force on all three blocks should be zero. Free body diagrams have been shown below (Only horizontal forces are shown)

For equilibrium of $B, T = f_{1} + f_{2} = 25 N$

For equilibrium of $C, F = T + f_{2} + f_{3} = 80 N$

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Laws of Motion 3 Question 24

Integer Answer Type Question

Answer:

इंजीनियरिंग की तैयारी

चिकित्सा तैयारी

एनसीईआरटी पुस्तकें और समाधान

महत्वपूर्ण संसाधन

अन्य संसाधन

पाठ्यक्रम

परीक्षा मंच

नमूना मॉक टेस्ट

सदस्यता

एनसीईआरटी व्यायाम वीडियो समाधान

Laws of Motion 3 Question 24

Integer Answer Type Question

Answer:

इंजीनियरिंग की तैयारी

चिकित्सा तैयारी

एनसीईआरटी पुस्तकें और समाधान

महत्वपूर्ण संसाधन

अन्य संसाधन

पाठ्यक्रम

परीक्षा मंच

नमूना मॉक टेस्ट

सदस्यता

एनसीईआरटी व्यायाम वीडियो समाधान

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