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⚛️ Physics  ·  Oscillations  ·  NEET & JEE

The equation x = 3 sin(πt) + 4 cos(πt) represents SHM. What is the amplitude?

Answer: 5 cm.

  • A 5 cm
  • B 7 cm
  • C 1 cm
  • D 12 cm

Correct answer: A. 5 cm

Explanation: This can be written as A sin(ωt + φ) where A = √(3² + 4²) = √(9+16) = √25 = 5 cm.

Displacement, Velocity, Acceleration in SHMx(t)v(t)a(t)v leads x by 90°; a is exactly out of phase with x (a = −ω²x)

In SHM, displacement and velocity are 90° out of phase (v is maximum when x=0, and zero when x is extreme), while acceleration is always exactly opposite in sign to displacement, consistent with a = −ω²x.

Concept context

Simple harmonic motion, spring-mass, pendulum, energy in SHM, and resonance.

Read the full Oscillations notes →