Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
1. On which of the following the jet Engine works?
[A] Conservation of energy
[B] Conservation of Linear Momentum
[C] Conservation of Mass
[D] Conservation of Angular momentum
Show Answer
Correct Answer: B [Conservation of Linear Momentum]
Notes:Conservation of Linear Momentum law says that if no external force acts on a system, then its total linear momentum remains conserved. In equation form, Momentum=mass*velocity. To increase the momentum of an object, we need to either increase its mass or velocity or both.
- Rockets work on law of conservation of momentum. As momentum in one direction is given to the rocket’s exhaust gases, momentum in the other direction is given to the rocket itself.
2. “Fermi” is a unit of which among the following?
[A] Mass
[B] Length
[C] Velocity
[D] Frequency
Show Answer
Correct Answer: B [Length]
Notes:
“Fermi” is the unit of length. The femtometre is an SI unit of length equal to 10⁻¹⁵ metres, which means a quadrillionth of one.
3. If a moving body turns its speed to 1.5 times, what will be the impact on its kinetic energy?
[A] will become 1.5 times
[B] will become 3 times
[C] will become 2.25 times
[D] will become 6 times
Show Answer
Correct Answer: C [will become 2.25 times]
Notes:
Kinetic Energy is a product of half the Mass times Velocity Squared. When the velocity is doubled, the Kinetic energy would go up four times. If velocity is tripled, kinetic energy would go up nine times. If velocity is increased by 1.5 times the Kinetic energy would go up by 1.5×1.5=2.25 times.
4. We can hear a whooshing sound when we hold a spiral conch shell near our ears. What is the most likely reason behind this?
[A] The sound we hear is echoing of our blood rushing through the blood vessels of our ear
[B] The sound is generated by air flowing through the shell – in and out
[C] The ambient noise around us resonates inside the shell
[D] None of the reasons mentioned in statements A, B or C is correct
Show Answer
Correct Answer: C [ The ambient noise around us resonates inside the shell]
Notes:
The most likely explanation for the wave-like noise is ambient noise from around us. The seashell that we hold just slightly above our ear captures this noise, which resonates inside the shell.
5. The spray bottles used as window or household cleaner or perfume spray works on:
[A] Capillary action
[B] Bernoulli’s Principle
[C] Pascal’s Law
[D] Stoke’s Law
Show Answer
Correct Answer: B [ Bernoulli’s Principle]
Notes:
When we press the top of bottle the pressure at top of the bottle decreases and hence, the velocity of liquid flow increases. Bernoulli’s Principle states that an increase in the speed of a fluid produces a decrease in pressure and that a decrease in the speed of a fluid produces an increase in pressure. The principle states that the total energy of a moving fluid remains constant at all times.
6. Which of the following is correct about the properties of Gravitational Forces?
[A] They are the strongest forces in nature
[B] They observe inverse square law
[C] Both a and b
[D] None
Show Answer
Correct Answer: B [They observe inverse square law]
Notes:
Gravitational Forces are the weakest forces in nature. They obey inverse square law as they vary inversely as the square of the distance between the two bodies. They are central forces and conservative forces. They operate over very long distances having an infinite range.
7. The force between charged particles is called as:
[A] Nuclear Force
[B] Gravitational Force
[C] Centrifugal Force
[D] Electromagnetic Force
Show Answer
Correct Answer: D [Electromagnetic Force]
Notes:
Electromagnetic force is the force between charged particles. It can be attractive for unlike charges and repulsive for like charges. It does not need any intervening medium to act and is enormously strong as compared to gravitational force.
8. Among the following units, which one represents the smallest measurement of length?
[A] Micron
[B] Nanometer
[C] Fermi
[D] Angstrom
Show Answer
Correct Answer: C [Fermi]
Notes:
In the presented choices, the Fermi stands as the smallest unit of length measurement. It is equal to 10^-15 m. Comparatively, 1 Micron equals 10^-6 m, 1 Nanometer equals 10^-9 m, and 1 Angstrom equivalent to 10^-10 m. All these units are commonly used to measure minuscule distances, particularly in the realm of nanotechnology and particle physics. However, the Fermi, named after the esteemed physicist Enrico Fermi, remains the smallest.
9. kg m2is the unit of which of the following physical quantities?
[A] Linear Momentum
[B] Angular Momentum
[C] Angular Impulse
[D] Moment of Inertia
Show Answer
Correct Answer: D [ Moment of Inertia ]
Notes:
kg m2is the unit of Moment of Inertia. The moment of inertia is a physical quantity which describes how easily a body can be rotated about a given axis. It is a rotational analogue of mass. Moment of Inertia = mass x (radius of gyration)2
10. Which of the following is true about displacement of an object?
[A] It is always equal to the distance travelled by the object
[B] It can be less than the distance travelled by the object
[C] It can be greater than the distance travelled by the object
[D] It always less than the distance travelled by the object
Show Answer
Correct Answer: B [It can be less than the distance travelled by the object]
Notes:
The displacement is the shortest distance between the initial and final position of an object in the given time. The displacement of an object is a vector quantity. It can be less than or equal to the distance but can never be greater than the distance travelled by that object
