1
JEE Main 2020 (Online) 4th September Morning Slot
Numerical
+4
-0
Change Language
A circular disc of mass M and radius R is rotating about its axis with angular speed $${\omega _1}$$ . If another stationary disc having radius $${R \over 2}$$ and same mass M is droped co-axially on to the rotating disc. Gradually both discs attain constant angular speed $${\omega _2}$$ the energy lost in the process is p% of the initial energy. Value of p is __________.
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2
JEE Main 2020 (Online) 4th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Blocks of masses m, 2m, 4m and 8m are arranged in a line on a frictionless floor. Another block of mass m, moving with speed v along the same line (see figure) collides with mass m in perfectly inelastic manner. All the subsequent collisions are also perfectly inelastic. By the time the last block of mass 8m starts moving the total energy loss is p% of the original energy. Value of 'p' is close to : JEE Main 2020 (Online) 4th September Morning Slot Physics - Center of Mass and Collision Question 78 English
A
37
B
77
C
87
D
94
3
JEE Main 2020 (Online) 4th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Match the $${{{C_P}} \over {{C_V}}}$$ ratio for ideal gases with different type of molecules :

Molecule Type CP/CV
(A) Monatomic (I) 7/5
(B) Diatomic rigid molecules (II) 9/7
(C) Diatomic non-rigid molecules (III) 4/3
(D) Triatomic rigid molecules (IV) 5/3
A
(A)-(III), (B)-(IV), (C)-(II), (D)-(I)
B
(A)-(IV), (B)-(II), (C)-(I), (D)-(III)
C
(A)-(IV), (B)-(I), (C)-(II), (D)-(III)
D
(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
4
JEE Main 2020 (Online) 4th September Morning Slot
Numerical
+4
-0
Change Language
In a compound microscope, the magnified virtual image is formed at a distance of 25 cm from the eye-piece. The focal length of its objective lens is 1 cm. If the magnification is 100 and the tube length of the microscope is 20 cm, then the focal length of the eye-piece lens (in cm) is __________.
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