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⁞ Physics

General Science ➤ Physics ➤ 2
Question 41
Q41.  When we go from Equator to North pole the value of acceleration due to gravity (g)__:
 

Answer :  increases


The acceleration due to gravity of earth is the rate of increase of velocity of a body falling freely towards the earth. At a given place, the value of acceleration due to gravity is constant but it varies from one place to another place on the earth surface. It is due to this fact that earth is not a perfect sphere. It is flattened at the poles and bulges out at the equator. Therefore, the value of ‘g’ is minimum at the equator and maximum at the poles.
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Question 42
Q42.  Which of the following is a scalar quantity ?
 

Answer :  Electrostatic potential


The electrostatic potential at any point in an electric field is defined as the work done in bringing a unit positive charge from infinity to that point against the electric force of the field. It is given by, V = W/q, where V is the potential, W is work done, and q the charge. Because work and charge both are scalar quantity, electrostatic potential is also a scalar quantity.
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Question 43
Q43.  When a man in a train moving with a constant velocity drops a ball on the platform, the path of the ball as seen by an observer on platform will be__:
 

Answer :  A parabola


In the reference frame of the platform the ball has initial horizontal velocity equal to the velocity of the train. The vertical direction is the same observed on the train because both observers agree that gravity is acting on the ball causing an acceleration g. But, in the platform’s reference frame it already had x-velocity, and the resultant path would be a parabola.
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Question 44
Q44.  What is the unit of relative density?
 

Answer :  It has no unit


Relative density is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. So, it is a dimensionless quantity and has no unit. Density of substance Density of water.
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Question 45
Q45.  The function of ball bearings in a wheel is__:
 

Answer :  to convert kinetic friction into rolling friction


A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. In general, it’s main function is to convert kinetic friction into rolling friction. It achieves this by using at least two races to contain the balls and transmit the loads through the balls.
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