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Concepts Of Physics MCQ Edition [Volume 1]
Exam
Concepts Of Physics MCQ Edition [Volume 1]
Subject
Physics
Chapter
Friction

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Friction

Consider the arrangement depicted in the figure. Determine the...

Consider the arrangement depicted in the figure. Determine the tension in the string attached to the 0.50 kg0.50 \text{ kg} block. (Assume g=10 m/s2g = 10 \text{ m/s}^2)
Consider the arrangement depicted in the figure. Determine the tension in the string attached to the 0.50 kg block.

Options

  1. A4.8 N4.8 \text{ N}
  2. B5.2 N5.2 \text{ N}
  3. C4.6 N4.6 \text{ N}
  4. D5.0 N5.0 \text{ N}

Correct answer

A. 4.8 N4.8 \text{ N}

Step-by-step solution

The maximum frictional force acting on the two blocks on the horizontal surface is given by:

f=μm1g+μm2gf = \mu m_1 g + \mu m_2 g

Substituting the given values:

f=0.2×1.0×10+0.2×1.0×10=2+2=4 Nf = 0.2 \times 1.0 \times 10 + 0.2 \times 1.0 \times 10 = 2 + 2 = 4 \text{ N}

The driving force due to the hanging block is:

W=m3g=0.5×10=5 NW = m_3 g = 0.5 \times 10 = 5 \text{ N}

Since the driving force is greater than the total frictional force (5 N>4 N5 \text{ N} > 4 \text{ N}), the system will accelerate. Let aa be the common acceleration of the system. The net force on the system is:

Fnet=W−f=5−4=1 NF_{\text{net}} = W - f = 5 - 4 = 1 \text{ N}

The total mass of the system is:

M=1.0+1.0+0.5=2.5 kgM = 1.0 + 1.0 + 0.5 = 2.5 \text{ kg}

The acceleration of the system is:

a=FnetM=12.5=0.4 m/s2a = \dfrac{F_{\text{net}}}{M} = \dfrac{1}{2.5} = 0.4 \text{ m/s}^2

Let TT be the tension in the string attached to the 0.50 kg0.50 \text{ kg} block. Considering the free body diagram of the 0.50 kg0.50 \text{ kg} block, the equation of motion is:

m3g−T=m3am_3 g - T = m_3 a

5−T=0.5×0.45 - T = 0.5 \times 0.4

5−T=0.25 - T = 0.2

T=5−0.2=4.8 NT = 5 - 0.2 = 4.8 \text{ N}
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