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
1
Why is a person capable of jumping to a greater height on the Moon compared to the Earth?
Answer:
The acceleration due to gravity in moon is smaller than that on the earth.
The acceleration due to gravity on the Moon is approximately one-sixth of that on Earth. Because the gravitational force pulling the person back toward the surface is significantly weaker on the Moon, the same amount of muscular effort results in a higher jump.
2
What is the primary physical force responsible for the Moon's orbital motion around the Earth?
Answer:
Gravitational force
The Moon remains in orbit around the Earth due to the gravitational attraction between the two bodies. According to Newton's law of universal gravitation, this force acts as the centripetal force required to keep the Moon in a curved path, preventing it from moving in a straight line into space.
3
What is the primary physical cause of tidal waves observed in the Earth's oceans?
Answer:
Gravitational Effect of Moon on Earth
Tidal waves are primarily caused by the gravitational pull exerted by the Moon on the Earth's oceans. This gravitational gradient creates a tidal bulge on the side of the Earth facing the Moon and on the opposite side, resulting in high tides.
4
Who was the first scientist to experimentally determine the value of the Universal Gravitational Constant (G)?
Answer:
Henry Cavendish
In 1798, Henry Cavendish conducted a famous experiment using a torsion balance to measure the extremely weak gravitational force between two lead spheres. This allowed him to calculate the value of the Universal Gravitational Constant (G) for the first time.
5
Evaluate the following assertion and reason: Assertion (A): Trees grow against gravity. Reason (R): Nature defines gravitational law.
Answer:
A is true but R is false
Trees grow vertically upward, which is against the direction of the gravitational force (geotropism). This assertion is true. However, the reason provided is scientifically vague and does not explain the biological mechanism of plant growth. Nature does not 'define' the law of gravity; rather, the law of gravity is a mathematical description of physical observations.
6
Which of the following statements accurately describe the mass of a substance?
Answer:
1 and 2
Mass is defined as the amount of matter in an object and is an invariant property, meaning it does not change based on location or gravitational field strength. Statement 3 is incorrect because mass is independent of gravity, unlike weight.
7
Which physicist is credited with formulating the law of universal gravitation, which describes force as following an inverse square relationship?
Answer:
Newton
Sir Isaac Newton formulated the law of universal gravitation, which states that every point mass attracts every other point mass with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This was famously published in his seminal work, the 'Philosophiæ Naturalis Principia Mathematica'.
8
What is the standard value for the acceleration due to gravity (g) on the surface of the Earth?
Answer:
9.8 m s-2
The acceleration due to gravity (g) represents the rate at which an object accelerates toward the center of the Earth in a vacuum. While this value varies slightly depending on latitude and altitude, the standard accepted value for scientific calculations is approximately 9.8 m/s². This constant is fundamental in classical mechanics for determining the weight of objects and analyzing free-fall motion near the Earth's surface.
9
Between which entities does the fundamental gravitational force act?
Answer:
two masses
Gravitational force is a fundamental interaction that attracts any two objects with mass. According to Newton's Law of Universal Gravitation, every point mass attracts every other point mass in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
10
Which celestial body serves as the primary source of heat for the Earth?
Answer:
sun
The Sun is the central star of our solar system and the primary source of energy for Earth. Through nuclear fusion in its core, it radiates vast amounts of energy across the electromagnetic spectrum, which warms the planet and sustains life.