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. These questions are part of GKToday’s 35000+ MCQs Bank Course in GKToday Android App
31. How do the Ball-bearings reduce the friction?
[A] Reducing the area of contact with the use of metallic balls
[B] Increasing the area of contact with the use of metallic balls
[C] Applying lubricants to the balls used
[D] None of the above
Show Answer
Correct Answer: A [Reducing the area of contact with the use of metallic balls]
Notes:
Bearings reduce the friction of certain moving parts by replacing sliding friction with rolling friction. They are used to provide better linear motion or rotation around a fixed axis. Roller bearings are typically cylinders similar to free rollers, while ball bearings are spheres that are held in a track.
32. Ice skating can be used to demonstrate that when ice is under pressure, its?
[A] Melting point is lowered
[B] Melting point is raised
[C] Melting point remains unchanged
[D] Coefficient of friction with metal is reduced
Show Answer
Correct Answer: A [Melting point is lowered]
Notes:
It is a common idea among people that skaters slide more easily on ice than other smooth surfaces because ice melts under the pressure exerted by the skates to produce a thin film of water.
33. Which of the following is the distance between the two successive nodes of a standing wave?
[A] 1
[B] 1/2
[C] 3/4
[D] 1/3
Show Answer
Correct Answer: B [1/2]
Notes:
In a stationary wave, the distance between two successive nodes (anti-nodes) is one half wavelengths. Therefore, the distance between a node and the immediate next anti-node is one fourth of a wavelength.
34. Which of the following is the normal temperature of human body on the Kelvin scale?
[A] 280
[B] 290
[C] 300
[D] 310
Show Answer
Correct Answer: D [310]
Notes:
Normal body temperature of human is 37° C. But when we convert 37° C into Kelvin it becomes 310 K because 0° C = 0°C + 273 = 273 K.
35. Which of the following pairs of physical quantities have the same dimensions?
[A] Force and Power
[B] Work and Power
[C] Work and Energy
[D] Momentum and Power
Show Answer
Correct Answer: C [Work and Energy]
Notes:
The term energy is used to describe the capacity of a system to do work on another system. Energy of all types (Surface tension, Kinetic, Potential etc.) have the same dimension and unit as that of work with same dimensional formula of M1L2T-2. In the SI system, both have the same units of Newton meter.
36. What is the time period of a seconds pendulum?
[A] 1 second
[B] 2 seconds
[C] 0’5 second
[D] 1’5 seconds
Show Answer
Correct Answer: B [2 seconds]
Notes:
A seconds pendulum is a pendulum whose period is precisely two seconds; one second for a swing in one direction and other second for the return swing, it has a frequency of 1/2 Hz. At standard gravity, its length is 0.994 m.
37. An object covers distance which is directly proportional to the square of the time. Its accelaration is
[A] increasing
[B] decreasing
[C] zero
[D] constant
Show Answer
Correct Answer: D [constant]
Notes:
When an object covers distance which is directly proportional to the square of the time, its acceleration is constant. This is seen in the cases of falling objects. This relation between time and distance was first observed by Galileo.
38. Which of the following quantity is a measure of inertia ?
[A] Velocity
[B] Acceleration
[C] Mass
[D] Weight
Show Answer
Correct Answer: C [Mass]
Notes:
Inertia is defined as resistance of any object to any change of state of motion. The tendency of an object to resist changes in its state of motion varies with mass. Mass of an object is the measure of inertia of that object. The more inertia that an object has, the more mass that it has. A more massive object has a greater tendency to resist changes in its state of motion.
39. What is the SI unit of frequency?
[A] Newton
[B] Watt
[C] Farad
[D] Hertz
Show Answer
Correct Answer: D [Hertz]
Notes:
The number of waves or vibrations passing through a point in one second is called Frequency. The SI (System International) Unit of Frequency is Hertz(Hz). It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves.
40. Law of Inertia is also known as _________.
[A] Newton’s fist law of motion
[B] Newton’s second law of motion
[C] Newton’s third law of motion
[D] None of these
Show Answer
Correct Answer: A [Newton’s fist law of motion]
Notes:
According to Newton’s First Law of Motion, an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This is also known as Law of Inertia.
