# 15 Lecture

## PHY101

### Midterm & Final Term Short Notes

## Oscillations – I

Oscillations are the repetitive motion of an object or a system about a fixed point or an equilibrium position. It is a common phenomenon that we see in our everyday life, such as the motion of a pendulum, the vibration of a guitar string, or th

**Important Mcq's**

Midterm & Finalterm Prepration

Past papers included

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**Which of the following is a necessary condition for simple harmonic motion?**

A) Force is directly proportional to velocity

B) Acceleration is directly proportional to position

C) Velocity is directly proportional to position

D) Acceleration is directly proportional to velocity

Answer: B) Acceleration is directly proportional to the position

**Which of the following is true for the displacement of a simple harmonic oscillator?**

A) It is directly proportional to the velocity of the oscillator.

B) It is directly proportional to the acceleration of the oscillator.

C) It is proportional to the square of the velocity of the oscillator.

D) It is proportional to the square of the acceleration of the oscillator.

Answer: B) It is directly proportional to the acceleration of the oscillator.

**A simple pendulum oscillates with a period T. If the length of the pendulum is doubled, what is the new period of oscillation**?

A) T/2

B) T

C) 2T

D) 4T

Answer: C) 2T

**The restoring force in a simple harmonic oscillator is given by F = -kx, where x is the displacement from equilibrium and k is the spring constant. What is the period of oscillation?**

A) T = 2?/k

B) T = ?/k

C) T = 2??(k/m)

D) T = ??(k/m)

Answer: D) T = ??(k/m)

**Which of the following quantities remains constant in simple harmonic motion?**

A) Amplitude

B) Frequency

C) Phase

D) Energy

Answer: D) Energy

**A mass attached to a spring oscillates with a period of 2 seconds. What is the frequency of oscillation?**

A) 1 Hz

B) 0.5 Hz

C) 2 Hz

D) 4 Hz

Answer: A) 1 Hz

**The amplitude of a simple harmonic oscillator is 0.2 m and its period is 5 seconds. What is the maximum velocity of the oscillator?**

A) 0.04 m/s

B) 0.2 m/s

C) 0.4 m/s

D) 1 m/s

Answer: C) 0.4 m/s

**The motion of a particle is described by the equation x = 3cos(2?t) where x is the displacement from equilibrium and t is time. What is the frequency of oscillation?**

A) 1 Hz

B) 2 Hz

C) 3 Hz

D) 4 Hz

Answer: B) 2 Hz

**The kinetic energy of a simple harmonic oscillator is maximum when the displacement is:**

A) At the equilibrium position

B) At the maximum displacement from the equilibrium

C) At the minimum displacement from equilibrium

D) The kinetic energy is the same at all points

Answer: A) At the equilibrium position

**The period of a simple pendulum of length L and mass m is given by T = 2??(L/g), where g is the acceleration due to gravity. If the length of the pendulum is doubled, what is the new period of oscillation?**

A) T

B) 2T

C) T/2

D) 4T

Answer: B) 2T

**Subjective Short Notes**

Midterm & Finalterm Prepration

Past papers included

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**What is an oscillation?**

**Ans:** An oscillation is the repetitive motion of an object or a system about a fixed point or an equilibrium position.

**What is the difference between amplitude and frequency?**

**Ans:** Amplitude is the maximum displacement of an oscillating object from its equilibrium position, while frequency is the number of oscillations per unit time.

**What is simple harmonic motion?**

**Ans:** Simple harmonic motion occurs when the restoring force is proportional to the displacement from the equilibrium position, and the motion is periodic and sinusoidal.

**What is Hooke's law?**

**Ans:** Hooke's law states that the force required to stretch or compress a spring is proportional to the displacement.

**What is the equation of motion for a simple harmonic oscillator?**

**Ans: **The equation of motion

**Define simple harmonic motion.**

**Answer:** Simple harmonic motion is a type of periodic motion where the displacement of an object is proportional to the force acting on it and is directed toward the equilibrium position. The motion is characterized by a constant frequency, amplitude, and sinusoidal waveform.

**What is the difference between a period and frequency of oscillation?**

**Answer: **Period and frequency are two different ways to describe the motion of a system undergoing oscillation. Period is the time required for one complete cycle of oscillation, whereas frequency is the number of complete cycles that occur per unit of time. They are related by the formula T = 1/f, where T is the period and f is the frequency.

**What is meant by the amplitude of an oscillation?**

**Answer:** Amplitude is the maximum displacement of an oscillating system from its equilibrium position. It is a measure of the extent to which the system deviates from its mean position during the course of its oscillation.

**What is resonance?**

**Answer:** Resonance occurs when an oscillating system is subjected to a periodic driving force that has the same frequency as its natural frequency of vibration. As a result, the amplitude of the oscillation of the system becomes very large, which can lead to catastrophic failure if not properly managed.

**What is the difference between damped and undamped oscillations?**

**Answer:** Damped oscillations occur when the amplitude of an oscillating system decreases over time due to the presence of friction or other dissipative forces. Undamped oscillations, on the other hand, occur when the amplitude of the oscillating system remains constant over time in the absence of any external forces.

**What is meant by the period of oscillation of a pendulum?**

**Answer: **The period of oscillation of a pendulum is the time required for the pendulum to complete one full oscillation, i.e., to swing from one extreme position to the other and back again.

**What is the relationship between the mass of an object and its period of oscillation in a simple harmonic oscillator?**

**Answer:** The period of oscillation of a simple harmonic oscillator is independent of the mass of the object undergoing oscillation. This is because the restoring force acting on the object is proportional to its displacement, not its mass.

**What is the relationship between the spring constant and the period of oscillation in a mass-spring system?**

**Answer: **The period of oscillation of a mass-spring system is directly proportional to the square root of the mass attached to the spring and inversely proportional to the square root of the spring constant. This relationship is given by the formula T = 2??(m/k), where T is the period, m is the mass, and k is the spring constant.

**What is meant by the term "phase" in the context of oscillations?**

**Answer: **Phase refers to the relative position of an oscillating system at a given point in time with respect to its starting position. It is often expressed in terms of the angle of displacement from the equilibrium position, or as a fraction of the period completed.

**What is the relationship between the period of a wave and its wavelength?**

**Answer: **The period of a wave is directly proportional to its wavelength and inversely proportional to its frequency. This relationship is given by the formula T = ?/f, where T is the period, ? is the wavelength, and f is the frequency.

### Oscillations – I

Oscillations are the repetitive motion of an object or a system about a fixed point or an equilibrium position. It is a common phenomenon that we see in our everyday life, such as the motion of a pendulum, the vibration of a guitar string, or the oscillation of a spring. In physics, oscillations are studied in great detail due to their wide range of applications in various fields. The motion of an oscillating object can be described by its amplitude, period, and frequency. The amplitude is the maximum displacement of the object from its equilibrium position, while the period is the time taken for one complete oscillation. The frequency is the number of oscillations per unit of time, measured in Hertz (Hz).### There are two types of oscillations:

Simple harmonic oscillations and non-simple harmonic oscillations. Simple harmonic oscillations occur when the restoring force is proportional to the displacement from the equilibrium position, and the motion is periodic and sinusoidal. Non-simple harmonic oscillations occur when the restoring force is not proportional to the displacement, and the motion is not sinusoidal. The most common example of the simple harmonic motion is the motion of a mass attached to a spring. When the spring is compressed or stretched, it exerts a restoring force on the mass that is proportional to the displacement from its equilibrium position. This results in a sinusoidal motion with a constant period and frequency. Other examples of simple harmonic motion include the motion of a pendulum and the vibration of a guitar string. The behavior of oscillating systems can be studied using Hooke's law, which states that the force required to stretch or compress a spring is proportional to the displacement. This law can be used to derive the equation of motion for a simple harmonic oscillator, which is given by:### x = A cos (?t + ?)

Where x is the displacement of the oscillator from its equilibrium position, A is the amplitude of the motion, ? is the angular frequency, t is time, and ? is the phase angle. The energy of an oscillating system is also an important concept. The total energy of an oscillating system is the sum of its kinetic energy and potential energy, which are constantly interchanging during the motion. At the maximum displacement from the equilibrium position, the kinetic energy is zero, and the potential energy is maximum. At the equilibrium position, the potential energy is zero, and the kinetic energy is maximum. The total energy of the system is conserved, and it oscillates between kinetic and potential energy.**In conclusion,**oscillations are a fundamental concept in physics with widespread applications in various fields such as mechanics, electronics, and acoustics. Simple harmonic motion is the most common type of oscillation, which occurs when the restoring force is proportional to the displacement. The motion of an oscillating object can be described by its amplitude, period, and frequency. The energy of an oscillating system is conserved and oscillates between kinetic and potential energy.