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. The ideal fluid which is a hypothetical fluid should contain _______?
[A] Zero Viscosity Only
[B] Zero Compressibility Only
[C] Zero Viscosity & Zero Compressibility
[D] None of the above
Show Answer
Correct Answer: C [Zero Viscosity & Zero Compressibility]
Notes:
An ideal fluid hypothetical fluid should contain Zero Viscosity & Zero Compressibility. Almost all fluids will not have zero viscosity and zero compressibility.
2. A person is standing in front of a wall and makes a sound. What should be the normal minimum distance between the person and the wall , so that the person hears echo?
[A] 6 meters
[B] 13 meters
[C] 20 meters
[D] 17 meters
Show Answer
Correct Answer: D [17 meters]
Notes:
To hear an echo, the minimum distance between a wall and the source of sound is 17m. The minimum interval is 0.1 sec.
3. In recent times, the “dynamic brake system” is becoming popular in modern railways. The dynamic brake system coverts Kinetic energy to__:
[A] Potential energy
[B] Electricity
[C] Sound energy
[D] Magnetic energy
Show Answer
Correct Answer: B [ Electricity]
Notes:
Modern engines also have, additionally, dynamic brake system which works on the principle of converting kinetic energy of the moving train to electricity making the electric motors to work as generators.
4. The recoiling of gun is an example of which of the following?
[A] Law of Conservation of Angular Momentum
[B] Law of Conservation of Linear Momentum
[C] Conversion of Kinetic Energy to Potential Energy
[D] Law of Conservation of Energy
Show Answer
Correct Answer: B [Law of Conservation of Linear Momentum]
Notes:
The recoiling of gun is an example of Law of Conservation of Linear Momentum. When gun fires a bullet, it experiences a force in forward direction (action) , as a result the gun exerts a backward force (reaction) on the shoulder. Thus, it is in accordance with Law of Conservation of Linear Momentum which is also the Newton’s 3rd law of motion.
5. Who among the following gave the Uncertainity principle?
[A] R.A Milkman
[B] Ernset Rutherford
[C] S.N Bose
[D] Werner Heisenberg
Show Answer
Correct Answer: D [Werner Heisenberg]
Notes:
Werner Heisenberg, a german Physicist, discovered the Uncertainity principle. As per the uncertainty principle, we cannot measure the position (x) and the momentum (p) of a particle with absolute precision. The more accurately we know one of these values, the less accurately we know the other. It represnts the effects of wave-particle duality on the properties of subatomic objects.
6. The acceleration at a given instant of time is called as:
[A] Average acceleration
[B] Instantaneous acceleration
[C] Variable acceleration
[D] Zero acceleration
Show Answer
Correct Answer: B [Instantaneous acceleration]
Notes:
The acceleration of an object at a given instant of time is called Instantaneous acceleration. When an object moves with variable acceleration, then it possesses different acceleration at different point of time.
7. The equation of motion ‘v = u +at’ can be applied in which of the following cases?
[A] simple harmonic motion
[B] circular motion
[C] when acceleration is constant
[D] Both b and c
Show Answer
Correct Answer: C [when acceleration is constant]
Notes:
The equation of motion ‘v = u +at’ can be applied only when the acceleration is constant. It cannot be applied in the cases of simple harmonic motion and circular motion.
8. Which of these is/are examples of conservation of linear momentum?
[A] Explosion of bomb
[B] Recoiling of a gun
[C] Fight of rockets and jet planes
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:Some examples of conservation of linear momentum:
- Recoiling of a gun
- Explosion of bomb
- Fight of rockets and jet planes
- A man jumping out of a boat to the shore
- A person on a frictionless surface
9. What will be the work done in holding a 25 kg iron plate for 25 seconds?
[A] 25 j
[B] 1 j
[C] 0
[D] 625 j
Show Answer
Correct Answer: C [0]
Notes:
The work done in holding a 25 kg iron plate for 25 seconds will be zero as there is no displacement taking place. Work done = Force x Displacement
10. Which of the following is true about the effect of altitude on the value of acceleration due to gravity?
[A] The acceleration due to gravity decreases with height
[B] The acceleration due to gravity increases with height
[C] The acceleration due to gravity is not dependent on height
[D] None of the above
Show Answer
Correct Answer: A [The acceleration due to gravity decreases with height]
Notes:
The acceleration due to gravity decreases with height. G0= g(1-2h/R) where h is the height above the surface of the earth.
