1
JEE Main 2018 (Offline)
+4
-1
Seven identical circular planar disks, each of mass M and radius R are welded symmetrically as shown. The moment of inertia of the arrangement about the axis normal to the plane and passing through the point P is :
A
$${{181} \over 2}M{R^2}$$
B
$${{55} \over 2}M{R^2}$$
C
$${{19} \over 2}M{R^2}$$
D
$${{73} \over 2}M{R^2}$$
2
JEE Main 2018 (Offline)
+4
-1
From a uniform circular disc of radius R and mass 9M, a small disc of radius R/3 is removed as shown in the figure. The moment of inertia of the remaining disc about an axis perpendicular to the plane of the disc and passing through centre of disc is :
A
$${{37} \over 9}M{R^2}$$
B
$$4M{R^2}$$
C
$${{40} \over 9}M{R^2}$$
D
$$10M{R^2}$$
3
JEE Main 2018 (Online) 15th April Evening Slot
+4
-1
A thin uniform bar of length $$L$$ and mass $$8$$ m lies on a smooth horizontal table. Two point masses m and 2 m are moving in the same horizontal plane from opposite sides of the bar with speeds 2$$\upsilon$$ and $$\upsilon$$ respectively. The masses stick to the bar after collision at a distance $${L \over 3}$$ and $${L \over 6}$$ respectively from the center of the bar. If the br starts rotating about its center of mass as a result of collision, the angular speed of the bar will be :
A
$${v \over {5L}}$$
B
$${6v \over {5L}}$$
C
$${3v \over {5L}}$$
D
$${v \over {6L}}$$
4
JEE Main 2018 (Online) 15th April Evening Slot
+4
-1
A thin rod MN, free to rotate in the vertical plane aboutthe fixed end N, is held horizontal. When the end M is released the speed of this end, when the rod makes an angle $$\alpha$$ with the horizontal, will be proportional to : (see figure)

A
$$\sqrt {\sin \alpha }$$
B
$${\sin \alpha }$$
C
$$\sqrt {\cos \alpha }$$
D
$${\cos \alpha }$$
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