1
JEE Main 2019 (Online) 11th January Evening Slot
+4
-1
A string is wound around a hollow cylinder of mass 5 kg and radius 0.5m. If the string is now pulled with a horizontal force of 40 N, and the cylinder is rolling without slipping on a horizontal surface (see figure), then the angular acceleration of the cylinder will be (Neglect the mass and thickness of the string) :

A
B
C
D
2
JEE Main 2019 (Online) 11th January Morning Slot
+4
-1
A slab is subjected to two forces $$\overrightarrow {{F_1}}$$ and $$\overrightarrow {{F_2}}$$ of same magnitude F as shown in the figure. Force $$\overrightarrow {{F_2}}$$ is in XY-plane while force $$\overrightarrow {{F_1}}$$ acts along z = axis at the point $$\left( {2\overrightarrow i + 3\overrightarrow j } \right).$$. The moment of these forces about point O will be :

A
$$\left( {3\widehat i - 2\widehat j - 3\widehat k} \right)F$$
B
$$\left( {3\widehat i + 2\widehat j - 3\widehat k} \right)F$$
C
$$\left( {3\widehat i + 2\widehat j + 3\widehat k} \right)F$$
D
$$\left( {3\widehat i - 2\widehat j + 3\widehat k} \right)F$$
3
JEE Main 2019 (Online) 11th January Morning Slot
+4
-1
An equilateral triangle ABC is cut from a thin solid sheet of wood. (see figure) D, E and F are the mid-points of its sides as shown and G is the centre of the triangle. The moment of inertia of the triangle about an axis passing through G and perpendicular to the plane of the triangle is I0. If the smaller triangle DEF is removed from ABC, the moment of inertia of the remaining figure about the same axis is I. then :

A
$${\rm I} = {{{{\rm I}_0}} \over 4}$$
B
$${\rm I} = {{15} \over {16}}{{\rm I}_0}$$
C
$${\rm I} = {9 \over {16}}{{\rm I}_0}$$
D
$${\rm I} = {3 \over 4}{{\rm I}_0}$$
4
JEE Main 2019 (Online) 10th January Evening Slot
+4
-1
A rigid massless rod of length 3l has two masses attached at each end as shown in the figure. The rod is pivoted at point P on the horizontal axis (see figure). When released from initial horizontal position, its instantaneous angular acceleration will be -

A
$${g \over {13l}}$$
B
$${g \over {2l}}$$
C
$${g \over {3l}}$$
D
$${7g \over {3l}}$$
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