SATHEE: Laws of Motion 3 Question 1

Laws of Motion 3 Question 1

1. Two blocks $A$ and $B$ of masses $m_{A} = 1 k g$ and $m_{B} = 3 k g$ are kept on the table as shown in figure. The coefficient of friction between $A$ and $B$ is 0.2 and between $B$ and the surface of the table is also 0.2 . The maximum force $F$ that can be applied on $B$

horizontally, so that the block $A$ does not slide over the block $B$ is

[Take, $g = 10 m / s^{2}$ ]

(2019 Main, 10 April II)

(a) $12 N$

(b) $16 N$

(d) $40 N$

Objective Question II (One or more correct option)

Show Answer

Answer:

Correct Answer: 1. (b)

Solution:

Acceleration $a$ of system of blocks $A$ and $B$ is

$a = \frac{Net force}{Total mass} = \frac{F - f_{1}}{m_{A} + m_{B}}$

where, $f_{1} =$ friction between $B$ and the surface

$= μ (m_{A} + m_{B}) g$

So,

$a = \frac{F - μ (m_{A} + m_{B}) g}{(m_{A} + m_{B})}$

Here, $μ = 0.2, m_{A} = 1 k g, m_{B} = 3 k g, g = 10 m s^{- 2}$

Substituting the above values in Eq. (i), we have

$\begin{aligned} a = \frac{F - 0.2 (1 + 3) \times 10}{1 + 3} \\ a = \frac{F - 8}{4} \end{aligned}$

Due to acceleration of block $B$ , a pseudo force $F^{'}$ acts on $A$ .

This force $F^{'}$ is given by $F^{'} = m_{A} a$

where, $a$ is acceleration of $A$ and $B$ caused by net force acting on $B$ .

For $A$ to slide over $B$ ; pseudo force on $A$ , i.e. $F^{'}$ must be greater than friction between $A$ and $B$ .

$\Rightarrow m_{A} a \geq f_{2}$

We consider limiting case,

$\begin{aligned} m_{A} a & = f_{2} \\ \Rightarrow & m_{A} a & = μ (m_{A}) g \\ \Rightarrow & = μ g = 0.2 \times 10 = 2 m s^{- 2} \end{aligned}$

Putting the value of $a$ from Eq. (iii) into Eq. (ii), we get

$\begin{aligned} \frac{F - 8}{4} & = 2 \\ ∴ F & = 16 N \end{aligned}$

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अगला

Laws of Motion 3 Question 1

1. Two blocks $A$ and $B$ of masses $m_{A} = 1 k g$ and $m_{B} = 3 k g$ are kept on the table as shown in figure. The coefficient of friction between $A$ and $B$ is 0.2 and between $B$ and the surface of the table is also 0.2 . The maximum force $F$ that can be applied on $B$

Objective Question II (One or more correct option)

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 1

1. Two blocks A and B of masses mA=1kg and mB=3kg are kept on the table as shown in figure. The coefficient of friction between A and B is 0.2 and between B and the surface of the table is also 0.2 . The maximum force F that can be applied on B

Objective Question II (One or more correct option)

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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1. Two blocks $A$ and $B$ of masses $m_{A} = 1 k g$ and $m_{B} = 3 k g$ are kept on the table as shown in figure. The coefficient of friction between $A$ and $B$ is 0.2 and between $B$ and the surface of the table is also 0.2 . The maximum force $F$ that can be applied on $B$