Laws of Motion 3 Question 4

4. Two masses $m _1=5 kg$ and $m _2=10 kg$ connected by an inextensible string over a frictionless pulley, are moving as shown in the figure. The coefficient of friction of horizontal surface is 0.15 . The minimum weight $m$ that should be put

on top of $m _2$ to stop the motion is

(2018 Main)

(a) $23.33 kg$

(b) $18.3 kg$

(c) $27.3 kg$

(d) $43.3 kg$

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Answer:

Correct Answer: 4. (a)

Solution:

  1. None of the four options are correct.

Substituting, $\quad m _1=5 kg$ and $m _2=10 kg$

We get, $\mu(10+m) g \geq 5 g \quad \Rightarrow \quad 10+m \geq \frac{5}{0.15}$

$$ m \geq 23.33 kg $$



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