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Practice MCQ Questions and answers on Physics-GK

Learn and practice General Knowledge questions and answers on Physics with very easy and understandable explanations. GK questions are very helpful different type of competitive exams. Page-9 section-8

Each section contains 100 MCQs on Physics .
81
What is the direction of torque?
Discuss
Answer & Solution
Answer: Option A
Solution:
The direction of torque is perpendicular to the direction of applied force.
82
The motion of a body around a circular path is an example of
Discuss
Answer & Solution
Answer: Option A
Solution:
Uniform circular motion occurs when a body moves in a circular path with constant velocity. The acceleration of a body experiencing uniform circular motion is always directed toward the center of the circle (centripetal acceleration or
ac = V2 / r
where v is the body’s velocity, and r is the radius of the circle). This acceleration is constant in magnitude but changes in direction, so, it is variable at every point of the circular path.
83
What should a person on a freely rotating turn table do to decrease his (angular) speed ?
Discuss
Answer & Solution
Answer: Option C
Solution:
When a person on a turn table will raise his hands, there will be increase in the momentum of inertia. Hence, the angular velocity of the turntable will decrease.
84
A sphere rolls down on two inclined planes of different angles but same height, it does so
Discuss
Answer & Solution
Answer: Option B
Solution:
A solid sphere rolls down two different inclined planes of the same height but of different inclinations. The speed and the of descend will be same.
85
If a body moves with a constant speed in a circle
Discuss
Answer & Solution
Answer: Option D
Solution:
If a body moves with a constant speed in a circle its velocity remains constant.
86
A disk and a sphere of same radius but different masses roll on two inclined planes of the same altitude and length. Which one of the two objects gets to the bottom of the plane first ?
Discuss
Answer & Solution
Answer: Option B
Solution:
The sphere will reach the bottom faster than the disk. It is because the disk has a higher rotational inertia than the solid:
I= mr²
I is the rotational inertia where m is the mass and r is the square of distance from the axis of rotation. in the case of disk I is greater due to r and more the I, more is the rotational K.E. Then for conservation of energy Translational K.E will be less.
mgh= K.E (T) + K.E (R)
so in case of sphere translational K.E will be more, meaning more final velocity and it will reach the bottom faster.
87
The washing machine works on the principle of
Discuss
Answer & Solution
Answer: Option D
Solution:
A washing machine by spinning at 800-1600 rpm helps soap and dirt with it to leave the surface of the cloth via centrifugal force and into outlet pipes hence utilizing centrifugation to both clean and partially dry the clothes loaded in it.
88
When an unbalanced force acts on an object
Discuss
Answer & Solution
Answer: Option D
Solution:
When an unbalanced force acts on an object it causes change in motion of the object, the speed and direction of the object changes and the object moves.
89
What type of force acts on a car moving around a curve?
Discuss
Answer & Solution
Answer: Option C
Solution:
As a car makes a turn, the force of friction acting upon the turned wheels of the car provides centripetal force required for circular motion. As a bucket of water is tied to a string and spun in a circle, the tension force acting upon the bucket provides the centripetal force required for circular motion.
90
Damp clothes are dried in spin dryers by the action of
Discuss
Answer & Solution
Answer: Option B
Solution:
The spin dryer is probably the most familiar centrifuge. The spin dryer of a washing machine removes excess water from the clothing by rotating at a high speed. The high speed of rotation creates a high centrifugal force for the water in the clothing which causes it to be pulled to the outside of the spinning portion of the washing machine and away from the clothes.