1
JEE Main 2013 (Offline)
+4
-1
A hoop of radius $$r$$ and mass $$m$$ rotating with an angular velocity $${\omega _0}$$ is placed on a rough horizontal surface. The initial velocity of the center of the hoop is zero. What will be the velocity of the center of the hoop when it cases to slip?
A
$${{r{\omega _0}} \over 4}$$
B
$${{r{\omega _0}} \over 3}$$
C
$${{r{\omega _0}} \over 2}$$
D
$${r{\omega _0}}$$
2
AIEEE 2011
+4
-1
A thin horizontal circular disc is rotating about a vertical axis passing through its center. An insect is at rest at a point near the rim of the disc. The insect now moves along a diameter of the disc to reach its other end. During the journey of the insect, the angular speed of the disc.
A
continuously decreases
B
continuously increases
C
first increases and then decreases
D
remains unchanged
3
AIEEE 2011
+4
-1
A mass $$m$$ hangs with the help of a string wrapped around a pulley on a frictionless bearing. The pulley has mass $$m$$ and radius $$R.$$ Assuming pulley to be a perfect uniform circular disc, the acceleration of the mass $$m,$$ if the string does not slip on the pulley, is:
A
$$g$$
B
$${2 \over 3}g$$
C
$${g \over 3}$$
D
$${3 \over 2}g$$
4
AIEEE 2011
+4
-1
A pulley of radius $$2$$ $$m$$ is rotated about its axis by a force $$F = \left( {20t - 5{t^2}} \right)$$ newton (where $$t$$ is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is $$10kg$$-$${m^2}$$ the number of rotation made by the pulley before its direction of motion is reversed, is:
A
more than $$3$$ but less than $$6$$
B
more than $$6$$ but less than $$9$$
C
more than $$9$$
D
less than $$3$$
EXAM MAP
Medical
NEET