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
41
What is the standard SI unit for momentum?
Answer:
kgms-1
Momentum (p) is defined as the product of mass (m) and velocity (v). Since mass is measured in kilograms (kg) and velocity in meters per second (m/s), the SI unit for momentum is kg·m/s, which is written as kgms^-1.
42
Which of the following statements most accurately describes the physical factors that determine the momentum of a moving object?
Answer:
The momentum of a moving object depends on its mass and velocity
Momentum (p) is defined as the product of an object's mass (m) and its velocity (v), expressed by the formula p = mv. Therefore, momentum is directly proportional to both the mass of the object and its velocity. Option B is the most comprehensive and accurate description of the physical definition of linear momentum.
43
When a ball bounces off a surface, which physical quantity undergoes an instantaneous change, assuming no energy loss?
Answer:
Its momentum
Momentum is a vector quantity (p = mv). When the ball hits the ground and reverses direction, its velocity vector changes sign, causing an instantaneous change in momentum, even if the speed remains constant.
44
Given that a proton, electron, neutron, and alpha particle all possess the same momentum, which particle exhibits the highest kinetic energy?
Answer:
Electron
Kinetic energy (K) is related to momentum (p) by the equation K = p^2 / (2m). Since the momentum p is constant for all particles, the kinetic energy is inversely proportional to the mass (m) of the particle. Because the electron has the smallest mass among the listed particles, it will have the highest kinetic energy.
45
Which physical quantity is determined by calculating the ratio of a body's momentum to its velocity?
Answer:
Mass
Linear momentum (p) is defined as the product of mass (m) and velocity (v), expressed as p = mv. Therefore, the ratio of momentum to velocity (p/v) yields the mass of the object. This relationship is fundamental in classical mechanics for defining inertia.
46
When a bullet is fired from a gun, how does the kinetic energy of the bullet compare to that of the gun?
Answer:
More than gun
By the law of conservation of momentum, the gun and bullet have equal and opposite momenta. Since KE = p² / (2m), and the bullet has a much smaller mass than the gun, the bullet must have a significantly higher kinetic energy to satisfy the momentum conservation requirement.
47
How is the force of impact defined in physical terms?
Answer:
When the objects meet
The force of impact refers to the impulsive force generated during the collision or physical contact between two objects. This force is typically characterized by a high magnitude acting over a very short duration, resulting in a significant change in the momentum of the colliding bodies as they interact.
48
Which mathematical formula correctly represents the calculation of momentum?
Answer:
momentum = mass × velocity
Momentum is a fundamental physical quantity defined as the product of the mass of a body and its velocity. It represents the inertia of motion and is a key concept in classical mechanics.
49
The product of an object's mass and its velocity is defined as which physical quantity?
Answer:
momentum
In classical mechanics, linear momentum (p) is defined as the product of an object's mass (m) and its velocity (v), expressed by the formula p = mv. It is a vector quantity that represents the quantity of motion an object possesses.
50
Which of the following physical quantities shares the same dimensional formula as impulse?
Answer:
Momentum
Impulse is defined as the change in momentum (Force × time). According to the impulse-momentum theorem, the impulse applied to an object is equal to the change in its momentum. Therefore, both quantities have the same dimensions of [M L T⁻¹].