Physics · Newton's Laws of Motion · Video solution

In the diagram shown; block A of mass 2 kg is hanging from the string passing over a smooth…

Question

In the diagram shown; block A of mass 2 kg is hanging from the string passing over a smooth pulley and block B is placed on the top of a table. If the reaction of the table is 10 N, mass of block B is : (g=10m/s²) (1) 1 Kg (2) 2 Kg (3) 3 Kg (4) 4 Kg

Answer

(3) 3 Kg

Concept: Newton's Laws, Pulley System

Step-by-step solution

  1. 1. Block A ka Tension

    Block A: Equilibrium • Net force = 0 • Tension = Weight

    T=mAgT = m_A g

  2. 2. Tension calculate karo

    mA=2kg•g=10m/s2•T=2∗10=20Nm_A = 2 kg • g = 10 m/s² • T = 2 * 10 = 20 N

    T=2×10=20 NT = 2 \times 10 = 20 \text{ N}

  3. 3. Block B par forces

    Block B: Equilibrium • Weight (m_B g) down • Tension (T) up

    NB+T=mBgN_B + T = m_B g

  4. 4. m_B calculate karo

    NB=10N•T=20N•10+20=mB∗10N_B = 10 N • T = 20 N • 10 + 20 = m_B * 10

    10+20=mB×1010 + 20 = m_B \times 10

  5. 5. Yaad rakho / Key takeaway

    Equilibrium mein net force zero hoti hai, forces ko balance karna seekho.

Remember

Equilibrium mein net force zero hoti hai, forces ko balance karna seekho.

Common mistake

Tension ko ignore karna ya normal reaction ki direction galat lena.

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