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26.4k views 4.9 unacademy Kumar Ketan #16 Educator in IIT JEE #6 years teaching experience #IT JEE Physics #YouTuber (150k+ subs) #Unacademy educator(25kt lifetimeviews) #Under graduate topper Follow me on the Unacademy Learning App 1.3k 2 26 Followers Following Courses Get updates about new courses Watch all my lessons .Download slides and watch offline Lists (1) Kumar Ketan HINDI IIT JEE Physics by Kumar Ketan for lIT JEE 8 4 saves Kumar Ketan

IIT JEE PHYSICS INDIAN IAN INSTITUTE 2018 Complete Paper Solution Q. #1 to Q. #30

QUESTION -1 1. The density of a material in the shape of a cube is determined by measuring three sides of the cube and its mass. If the relative errors in measuring the mass and length are respectively 1.5% and 1%, the maximum error in determining the density is (1) 2.5% (3) 4.5% (2) 3.5% (4) 6% HPA dp dmd m l =(1.5 + 3 x 1) = 4.5%

QUESTION - 2 All the graphs below are intended to represent the same motion. One of them does it incorrectly. Pick it up. Velocity Position Position (3)Time Distance Velocity Time (4)Time

Options (1), (3) and (4) correspond to uniformly accelerated motion in a straight line with positive initial velocity and constant negative acceleration, whereas option (2) does not correspond to this motion.

QUESTION - 3 Two masses m1- 5 kg and m2- 10 kg, connected by an inextensible string over a frictionless pulley, are moving as shown in the figure. The coefficient of friction of horizontal surface is 0.15. The minimum weight m that should be put on top of m2 to stop the motion is m2 m, (1) 18.3 kg (2) 27.3 kg (3) 43.3 kg (4) 10.3 kg m.g

5 <0.15(m 10) m > 23.33 kg Minimum mass 27.3 kg (according to given options)

QUESTION -4 A particle is moving in a circular path of radius a under the action of an attractive potential U =-k/2r2. Its total energy IS (1)4a2 (2) 2a (3) Zero (4) 2 a 3 k

-du dr Sol. F= 2r2 mv2 k [This force provides necessary centripetal force] 3 2 r2 KE- 2r2 2r2 Total energy = Zero

Sol. It is a case of superelastic collision 2 .2 2 2 2 2 12 2

MR2 MR2 Sol 6 .MC2RY) lp = 10 + 7 M3RF 181 MR2 2