Physics MCQs
Topic Notes: Physics
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
81
What is the mathematical product of the frequency and the time period of an oscillation?
Answer:
1
The frequency (f) of an oscillation is defined as the number of cycles per unit time, while the time period (T) is defined as the time taken for one complete cycle. By definition, frequency is the reciprocal of the time period (f = 1/T). Therefore, the product of frequency and time period is always equal to 1, representing the fundamental relationship between these two inverse variables.
82
How does the addition of wax to the prong of a tuning fork affect its oscillation frequency?
Answer:
decreases
The frequency of a tuning fork is inversely proportional to the square root of its mass. By adding wax to the prong, the effective mass of the oscillating system increases. According to the physics of simple harmonic motion, an increase in mass while the stiffness remains constant results in a lower natural frequency of vibration.
83
How is Simple Harmonic Motion (SHM) formally classified in physics?
Answer:
Periodic motion
Simple Harmonic Motion is a specific type of periodic motion where the restoring force acting on an object is directly proportional to its displacement from the equilibrium position and is directed toward that position. Because the motion repeats itself at regular intervals of time, it is fundamentally categorized as periodic or oscillatory motion.
84
What is the instantaneous velocity of an object undergoing simple harmonic motion when it reaches its extreme displacement position?
Answer:
zero
In simple harmonic motion (SHM), an object oscillates between two extreme points. At these extreme positions, the object momentarily stops before reversing its direction of motion. Since velocity is the rate of change of displacement, and the object is stationary at the turning point, its instantaneous velocity is zero, while its acceleration is at its maximum magnitude.
85
What is the term for the maximum displacement of an oscillating object from its equilibrium position?
Answer:
amplitude
In periodic motion, the amplitude is defined as the magnitude of the maximum displacement from the mean or equilibrium position. It is a key parameter that characterizes the energy and intensity of the oscillation.
86
Calculate the length of a simple pendulum that has a time period of 2 seconds.
Answer:
1.02m
The time period of a simple pendulum is given by T = 2π√(L/g). Rearranging for length L gives L = gT² / (4π²). Using g ≈ 9.8 m/s² and T = 2 s, we get L = (9.8 * 4) / (4 * 9.87) ≈ 0.994 m, which is approximately 1.02 m depending on the precise value of g used.
87
If a vibrating body covers a total distance of 20 cm during one complete oscillation cycle, what is its amplitude?
Answer:
5 cm
In simple harmonic motion, one complete cycle or oscillation consists of moving from the equilibrium position to the maximum positive displacement, back to equilibrium, to the maximum negative displacement, and returning to equilibrium. This path covers a total distance equal to four times the amplitude (4A). Given the total distance is 20 cm, the amplitude A = 20 cm / 4 = 5 cm.
88
How is simple harmonic motion formally categorized in physics?
Answer:
Periodic motion
Simple harmonic motion is a specific type of periodic motion where the restoring force is directly proportional to the displacement from the equilibrium position and acts in the opposite direction. Because the motion repeats itself at regular, predictable time intervals, it is classified as periodic or oscillatory motion.
89
Why do pendulum clocks typically lose time during the summer months?
Answer:
The length of the pendulum increases, increasing the time period of unit oscillation
The time period of a simple pendulum is T = 2π√(L/g). In summer, thermal expansion causes the pendulum rod to increase in length (L). As the length increases, the time period T also increases, meaning each oscillation takes longer. Consequently, the clock ticks more slowly, resulting in a loss of time.
90
What term describes a single complete round trip of an oscillating object about its equilibrium position?
Answer:
vibration
In the context of oscillatory motion, a vibration (or oscillation) is defined as one complete cycle of motion, starting from the mean position, moving to one extreme, returning through the mean to the other extreme, and finally returning to the starting mean position. Frequency is the number of such cycles per unit time, while the time period is the duration of one cycle.