Question 1

List I describes four systems, each with two particles A  and B  in relative motion as shown in figure. List II gives possible magnitudes of their relative velocities (in m &#160; s - 1 ) at

Accepted Answer

(I) Angular velocity of both the particles is same. Therefore, angle between them will remain  90 &#176; . v r e l = 2 &#969; R = 2 &#160; m &#160; s - 1 Hence,  I &#8594; S (II) The velocity of A at any time t can be written as v A t = 5 &#960; 2 cos 45 &#176; i ^ + 5 &#960; 2 &#215; sin 45 &#176; - g &#215; t j ^ = 5 &#960; 2 i ^ + 5 &#960; 2 - g t j ^ Velocity of B at any time t v B t = - 5 &#960; 2 i ^ + 5 &#960; 2 - g t - 0 . 1 j ^ Relative velocity at time t will be, v &#8594; r

Question 2

A point charge q of mass m is suspended vertically by a string of length l . A point dipole of dipole moment p → is now brought towards q from infinity so that the charge moves away. The final equilib

Accepted Answer

W = q V + m g h = q k p x 2 + m g h . . . 1 For equilibrium q E sin β = m g sin 90 - α 2 q E sin ( 180 - α ) = m g cos α 2 ; q E sin α = m g cos α 2 9 E 2 sin α 2 cos α 2 = m g cos α 2 ; q E = 2 mg sin α 2 q k p x 2 = m g x sin ( α 2 ) = m g sin α 2 · h sin α 2 q k p x 2 = m g h . . . 2 From (1) and (2) W = 2 m g h x = 2

Work Power Energy — Previous Year Questions & Solutions