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Physics Question 35 – JEE-MAIN 2026

The equation of a plane progressive wave is given by y=5cosπ(200tx150) where x and y are in cm and t is in second. The velocity of the wave is _______ m/s.

Recall the general form of a progressive wave equation, y=Acos(ωtkx), and identify its components from the given equation.

Step 1: Identify Wave Parameters✦ Active

The given equation of the plane progressive wave is y=5cosπ(200tx150). Expand the equation to match the standard form y=Acos(ωtkx):

y=5cos(200πtπx150)

Comparing this with the standard form, we identify the angular frequency ω and the wave number k:

ω=200π rad/s
k=π150 rad/cm
Step 2: Calculate Wave Velocity○ Expand

The velocity of the wave v is given by the ratio of the angular frequency to the wave number:

v=ωk

Substitute the values of ω and k:

v=200π rad/sπ150 rad/cm=200×150 cm/s
v=30000 cm/s
Step 3: Convert Units to m/s○ Expand

The question asks for the velocity in m/s. Since 1 m=100 cm, we convert the velocity from cm/s to m/s:

v=30000 cm/s×1 m100 cm
v=300 m/s
💡 Teacher's Secret Hint

Always double-check the required units for the final answer and perform necessary conversions.

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