Stage–2 | Page–10
SHM Graphs – x–t, v–t, a–t (JEE Advanced Level)

Most conceptual + multi-correct topic in SHM

Shm poster used in iit material



Fundamental SHM Equations

x = A sin(ωt + φ)
v = Aω cos(ωt + φ)
a = −ω²x
  • All SHM graphs are phase-shifted versions of each other
  • Amplitude and frequency are fixed

Displacement–Time (x–t) Graph

  • Pure sine or cosine wave
  • Period = T
  • Slope at any point = velocity
Key Points:
At mean position → slope maximum
At extreme position → slope zero

IIT Trap #1 – Slope Confusion

  • Slope ≠ speed (it is velocity)
  • Sign of slope matters

Velocity–Time (v–t) Graph

  • Cosine graph if x is sine
  • Phase difference of π/2 with x–t graph
Maximum velocity = Aω

Area under v–t graph = displacement


IIT Trap #2 – Area Under Curve

  • Positive area ≠ total distance
  • Opposite signs cancel
Distance requires absolute area

Acceleration–Time (a–t) Graph

  • Also sinusoidal
  • Always opposite in phase to x–t graph
a = −ω²x
When x is maximum → a is maximum (opposite sign)

Phase Relationship Summary

Graph Pair Phase Difference
x and v π/2
v and a π/2
x and a π

JEE Advanced Multi-Correct Logic

  • Same x → same a
  • Same |v| ≠ same position
  • Same graph shape ≠ same phase

Time Calculation from Graphs

  • Use periodicity
  • Use symmetry (half / quarter cycle)
  • Avoid calculus unless forced
Graph problems reward visualization, not formulas

Frequently Asked Advanced Questions

  • Matching x–t with v–t graphs
  • Finding acceleration from slope
  • Area interpretation traps
  • Counting zero crossings

Topper Strategy

  • Always mark mean & extreme positions
  • Note direction of motion
  • Use phase shift mentally

What Comes Next?

  • Stage–3: Energy Graphs in SHM
  • Advanced PYQs with graphs
  • Multi-body SHM systems

Stage–2 Completed ✔ You have crossed the hardest conceptual zone 🚀

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