1for 1st-b, for 2nd-c
am i right?
1.select the correct alternatives
(a)Work done by the friction is always zero.
(b)Work down by the kinetic friction can be positive
(c)Kinetic energy of the system can not be increased without applying any external force
(d)Work energy theorem is valid in non - inertial frames also
2.Work done by a force on an object is zero, if -
(a) the force is always perpendicular to its acceleration
(b) the object is stationary but the point of application of the force moves on the object
(c)the force is always perpendicular to its velocity
(d)the object moves in such a way that the point of application of the force remain fixed
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6 Answers
1Let me mix up ur ans....
ans to Q-1 are (b) (during walking)
(d) (by including work done by the pseudo force)
491) a and d
look u can argue that during walking,
but in that case, the point of application of force doesnt move in direction of force....
hence work done is 0!!
and d is correct for obvious reasons!!!
