1
JEE Main 2020 (Online) 4th September Morning Slot
Numerical
+4
-0
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 __________.
2
JEE Main 2020 (Online) 3rd September Evening Slot
Numerical
+4
-0
An massless equilateral triangle EFG of side ‘a’ (As shown in figure) has three particles of mass m situated at its vertices. The moment of inertia of the system about the line EX perpendicular to EG in the plane of EFG is $${N \over {20}}$$ ma2 where N is an integer. The value of N is _____.
3
JEE Main 2020 (Online) 3rd September Morning Slot
Numerical
+4
-0
A person of 80 kg mass is standing on the rim of a circular platform of mass 200 kg rotating about its axis at 5 revolutions per minute (rpm). The person now starts moving towards the centre of the platform. What will be the rotational speed (in rpm) of the platform when the person reaches its centre _________.
4
JEE Main 2020 (Online) 2nd September Evening Slot
Numerical
+4
-0
A square shaped hole of side l = $${a \over 2}$$ is carved out at a distance d = $${a \over 2}$$ from the centre ‘O’ of a uniform circular disk of radius a. If the distance of the centre of mass of the remaining portion form O is $$- {a \over X}$$ , value of X (to the nearest integer) is :
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