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
31
If an identical force is applied to two objects of different masses for the same duration, which physical quantity remains the same for both?
Answer:
Momentum
According to the impulse-momentum theorem, the impulse applied to an object is equal to the change in its momentum. Impulse is defined as the product of force and time (F × Δt). Since both the force and the time interval are identical for both objects, the impulse delivered to each object is the same, resulting in an identical change in momentum for both.
32
Two objects, A and B, move with identical velocities. If the mass of object B is twice that of object A, how does the momentum of B compare to that of A?
Answer:
Momentum of B will be double that of A
Momentum (p) is defined as the product of mass (m) and velocity (v), expressed as p = mv. Since both objects have the same velocity, the momentum is directly proportional to the mass. Given that the mass of B is twice the mass of A (mB = 2mA), it follows that the momentum of B must be twice the momentum of A (pB = 2pA).
33
Which fundamental physical principle governs the propulsion mechanism of a rocket?
Answer:
Conservation of momentum
A rocket operates based on the principle of conservation of linear momentum. As the rocket expels exhaust gases at high velocity in one direction, it experiences an equal and opposite reaction force, known as thrust, which propels the rocket forward. Since the total momentum of the system (rocket plus fuel) remains constant in the absence of external forces, the rocket gains forward momentum.
34
Which physical properties of an object determine its momentum?
Answer:
Both A & B
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. Since momentum is a vector quantity, it depends directly on both the scalar property of mass, which represents the object's inertia, and the vector property of velocity, which describes the object's speed and direction of motion.
35
How is the physical quantity known as momentum mathematically defined?
Answer:
mass and velocity
Momentum is a vector quantity defined as the product of an object's mass and its velocity. It represents the quantity of motion an object possesses. Mathematically, it is expressed as p = mv, where m is mass and v is velocity.
36
Which physical quantity is defined as the time rate of change of linear momentum?
Answer:
force
According to Newton's Second Law of Motion, the net force acting on an object is equal to the rate of change of its momentum with respect to time. Mathematically, this is expressed as F = dp/dt. This relationship provides a more generalized definition of force that applies even when mass is changing, such as in rocket propulsion.
37
What will be the momentum of an object of mass $$\frac{m}{2}$$ and whose velocity is 2v?
Answer:
mv
Source answer preserved: option B (mv). AI attempted to change protected answer data (option_c), so this item is flagged for manual review before study use.
38
How does the momentum of a moving object change when its velocity is doubled?
Answer:
its momentum is doubled
Momentum is defined as the product of mass and velocity (p = mv). If the mass remains constant and the velocity is doubled, the new momentum becomes p' = m(2v) = 2mv, which is exactly twice the original momentum. While kinetic energy (K.E = 1/2mv^2) would quadruple, the momentum increases linearly with velocity.
39
Given several particles with the same kinetic energy, which one possesses the greatest momentum?
Answer:
α-particle
The relationship between kinetic energy (K) and momentum (p) is given by p = sqrt(2mK). For a constant kinetic energy, momentum is directly proportional to the square root of the mass (p ∝ sqrt(m)). Since the α-particle has the largest mass among the listed particles (electron, proton, deuteron, and α-particle), it will have the highest momentum for a given kinetic energy.
40
According to Newton's Second Law of Motion, the net force acting on an object is directly proportional to the rate of change of which physical quantity?
Answer:
momentum
Newton's Second Law states that the net force applied to an object is equal to the time rate of change of its linear momentum. Mathematically, F = dp/dt. Since momentum is mass times velocity, this change in momentum results in acceleration for constant mass.