Physics Circle home Student Login

Home›Chapters›Wave Motion PYQs›Speed of Waves›Question 30

JEE Main 2020 (3 Sep, Shift 1) · Speed of Waves

Speed of Waves question from JEE Main 2020 (3 Sep, Shift 1)

Q30JEE Main 2020 · 3 SEP · SHIFT 1Medium

Speed of Waves

A uniform thin rope of length 12 m and mass 6 kg hangs vertically from a rigid support and a block of mass 2 kg is attached to its free end. A transverse short wavetrain of wavelength 6 cm is produced at the lower end of the rope. What is the wavelength of the wavetrain (in cm) when it reaches the top of the rope?

Show answer and solution

Answer: (a)

  1. λ∝T\lambda \propto \sqrt{T} (frequency unchanged).
  2. Bottom T=2gT = 2g, top T=(6+2)g=8gT = (6+2)g = 8g, so λtop=68/2=12\lambda_{top} = 6\sqrt{8/2} = 12 cm.
  3. So the answer is (a) 12.
Report a mistake

More questions on Speed of Waves