A particle oscillates along the x-axis according to the law, x(t) = x₀ ²((t)/(2)) where x₀ = 1 m . The kinetic energy (K) of the particle as a function of x is correctly represented by the graph.

Solution & Explanation

Related Formula
x(t) = x₀ ²((t)/(2)) = x₀ ((1 - t)/(2))
Core Logic

Given x₀ = 1 m, the position simplifies to:

x = (1 - t)/(2) 2x - 1 = - t t = 1 - 2x

Differentiating x(t) to find velocity v:

v = (dx)/(dt) = (1)/(2) t

Kinetic energy K is proportional to v²:

K = (1)/(2)mv² = (1)/(2)m ((1)/(4) ² t) = (m)/(8)(1 - ² t)

Substituting t = 1 - 2x:

K = (m)/(8)[1 - (1 - 2x)²] = (m)/(8)[1 - (1 - 4x + 4x²)] = (m)/(8)(4x - 4x²) = (m)/(2)(x - x²)

This is an inverted parabola (K ∝ x - x²) passing through x=0 and x=1, reaching a peak at x = 1/2. This matches Graph (1).

Pattern Recognition

The position oscillates purely within the boundary interval [0, 1]. Kinetic energy peaks perfectly at the equilibrium midpoint x = 1/2 where speed is maximum.

Chapter Mix

Class 11 Physics: Oscillations

Reference Study Guides

More Oscillations Previous-Year Questions — Page 3

Q13 jee_main_2025_24_jan_morning Simple Harmonic Motion
A particle is executing simple harmonic motion with time period 2s and amplitude 1 cm. If D and d are the total distance and displacement covered by the particle in 12.5 s, then (D)/(d) is:-
  • A. (15)/(4)
  • B. 25
  • C. 10
  • D. (16)/(5)

Solution

Related Formula

In Simple Harmonic Motion:

  • In one full oscillation period T, total distance = 4A, and net displacement = 0.
  • In a quarter period (T)/(4) starting from equilibrium, distance = A, and displacement = A.
Core Logic

Find the total number of cycles completed in the given time :

Cycles = (t)/(T) = 12.5 s2 s = 6.25 cycles = 6 full cycles + 0.25 cycle
Step 1: Evaluation of Distance and Displacement

Calculate the total distance D covered :

D = 6 × (4A) + 1A = 24A + A = 25A

Given amplitude A = 1 cm , we get D = 25 cm .

Calculate the net displacement d: The first 6 complete cycles return the particle to equilibrium with zero displacement. The remaining 0.25 cycle (which is a quarter period (T)/(4)) moves it from the center to its maximum amplitude value :

d = 1A = 1 cm

Taking their ratio:

(D)/(d) = (25)/(1) = 25
Pattern Recognition

Fractional cycles modulate ratios abruptly. Always break the path index down into integer full cycles plus the final residual interval.

Chapter Mix

Class 11 Physics: Oscillations

Q12 jee_main_2025_28_jan_evening Simple Harmonic Motion
Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Knowing initial position x₀ and initial momentum p₀ is enough to determine the position and momentum at any time t for a simple harmonic motion with a given angular frequency ω . Reason (R) : The amplitude and phase can be expressed in terms of x₀ and p₀ . In the light of the above statements, choose the correct answer from the options given below:
  • A. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
  • B. (A) is false but (R) is true.
  • C. (A) is true but (R) is false.
  • D. Both (A) and (R) are true and (R) is the correct explanation of (A).

Solution

Related Formula

The general solution tracking position in SHM is given by :

x(t) = A (ω t + φ)

Momentum formula:

p(t) = m v(t) = m A ω (ω t + φ)
Core Logic

At t = 0 :

  • x₀ = A φ
  • p₀ = m A ω φ
  • Dividing equation (1) by (2) reveals the phase \angle relationship :

φ = ((x₀)/(p₀)) m ω φ = ⁻¹((m ω x₀)/(p₀))

Squaring and combining both equations isolates amplitude A:

A = √((m ω x₀)² + p₀²)m ω

Since both amplitude A and phase constant φ are explicitly fixed by the initial conditions x₀ and p₀, the kinematic layout of the state space is completely specified for any future time parameter t. This validates that Reason (R) perfectly explains Assertion (A).

Pattern Recognition

SHM is a second-order differential equation. Any system of second-order equations requires exactly two independent boundary conditions (e.g., initial position and velocity/momentum) to completely specify unique path tracks.

Chapter Mix

Class 11 Physics: Oscillations

Q jee_main_2025_29_jan_morning Simple Pendulum
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Time period of a simple pendulum is longer at the top of a mountain than that at the base of the mountain. Reason (R) : Time period of a simple pendulum decreases with increasing value of acceleration due to gravity and vice-versa. In the light of the above statements, choose the most appropriate answer from the options given below:
  • A. Both (A) and (R) are true but (R) is not the correct explanation of (A).
  • B. Both (A) and (R) are true and (R) is the correct explanation of (A).
  • C. (A) is true but (R) is false.
  • D. (A) is false but (R) is true.

Solution

Related Formula
T = 2π√((l)/(g))
Core Logic

As altitude h increases at the top of a mountain, acceleration due to gravity g drops down according to :

g = (g₀ R²)/((R+h)²)

Since T ∝ 1√(g), a decreased g directly makes the time period T longer

Pattern Recognition

Higher altitude smaller gravity field slower pendulum oscillations longer period

Chapter Mix

Class 11 Physics: Oscillations Class 11 Physics: Gravitation

Q jee_main_2024_29_january_evening Simple Harmonic Motion
A simple harmonic oscillator has an amplitude A and time period 6π second. Assuming the oscillation starts from its mean position, the time required by it to travel from x = A to x = √(3)2A will be (π)/(x) s, where x = ________.
Numerical Answer. Answer: 2 to 2

Solution

Related Formula

For a simple harmonic oscillator starting from the mean position at t = 0:

x(t) = A (ω t)

where ω = (2π)/(T) is the angular frequency.

Core Logic

Given:

  • Time period, T = 6π s ω = (2π)/(6π) = (1)/(3) rad/s
  • We need to find the time taken to travel from x = A to x = √(3)2A. Let's calculate the times from the mean position (x=0) to both positions:

  • Time t₁ to reach x = A:
A = A (ω t₁) (ω t₁) = 1 ω t₁ = (π)/(2)
  • Time t₂ to reach x = √(3)2A:
√(3)2A = A (ω t₂) (ω t₂) = √(3)2 ω t₂ = (π)/(3)
Step 1: Calculate the Time Difference

The time required to travel between these two points is:

Δ t = t₁ - t₂ = (π/2)/(ω) - (π/3)/(ω) = (π)/(6ω)

Substitute ω = (1)/(3):

Δ t = (π)/(6 × (1/3)) = (π)/(2) seconds

Comparing this to (π)/(x) s, we find:

x = 2

Phasor diagram for SHM positions for Q55
Phasor diagram for SHM positions for Q55

Pattern Recognition

Alternatively, using a phasor diagram, the angle swept in moving from A to √(3)2A is φ = (π)/(6). Therefore, Δ t = (φ)/(ω) = (π/6)/(1/3) = (π)/(2) s.

Chapter Mix

Class 11 Physics: Oscillations

Q57 jee_main_2024_27_jan_morning Velocity in Simple Harmonic Motion
A particle executes simple harmonic motion with an amplitude of 4 cm. At the mean position, the velocity of the particle is 10 cm/s. The distance of the particle from the mean position when its speed becomes 5 cm/s is √(α) cm, where α = ______.
Numerical Answer. Answer: 12 to 12

Solution

Related Formula
vmax = Aω v = ω √(A² - x²)
Core Logic

From the mean position maximum criteria (vmax = 10 cm/s, A = 4 cm):

10 = 4ω ω = (10)/(4) = (5)/(2) rad/s
Step 1: Substitute parameters into speed equation

Set the target speed v = 5 cm/s:

5 = (5)/(2) √(4² - x²) 2 = √(16 - x²)

Squaring both sides:

4 = 16 - x² x² = 12 x = √(12) cm
Step 2: Compare to target format

Comparing √(12) to √(α) directly shows:

α = 12

Pattern Recognition

Halving the peak harmonic velocity maps spatial points directly to √(3)2A values through standard trigonometric projection balances.

Chapter Mix

Class 11 Physics: Oscillations

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