1
JEE Main 2021 (Online) 20th July Morning Shift
+4
-1
A steel block of 10 kg rests on a horizontal floor as shown. When three iron cylinders are placed on it as shown, the block and cylinders go down with an acceleration 0.2 m/s2. The normal reaction R' by the floor if mass of the iron cylinders are equal and of 20 kg each, is ____________ N. [Take g = 10 m/s2 and $$\mu$$s = 0.2]

A
686
B
684
C
714
D
716
2
JEE Main 2021 (Online) 16th March Morning Shift
+4
-1
A block of mass m slides along a floor while a force of magnitude F is applied to it at an angle $$\theta$$ as shown in figure. The coefficient of kinetic friction is $$\mu$$k. then, the block's acceleration 'a' is given by :

(g is acceleration due to gravity)

A
$${F \over m}\cos \theta + {\mu _K}\left( {g - {F \over m}\sin \theta } \right)$$
B
$${F \over m}\cos \theta - {\mu _K}\left( {g - {F \over m}\sin \theta } \right)$$
C
$$-$$$${F \over m}\cos \theta - {\mu _K}\left( {g - {F \over m}\sin \theta } \right)$$
D
$${F \over m}\cos \theta - {\mu _K}\left( {g + {F \over m}\sin \theta } \right)$$
3
JEE Main 2021 (Online) 26th February Evening Shift
+4
-1
Two masses A and B, each of mass M are fixed together by a massless spring. A force acts on the mass B as shown in the figure. If the mass A starts moving away from mass B with acceleration 'a', then the acceleration of mass B will be :

A
$${{MF} \over {F + Ma}}$$
B
$${{F + Ma} \over M}$$
C
$${{Ma - F} \over M}$$
D
$${{F - Ma} \over M}$$
4
JEE Main 2021 (Online) 24th February Evening Shift
+4
-1
A particle is projected with velocity v0 along x-axis. A damping force is acting on the particle which is proportional to the square of the distance from the origin i.e. ma = $$-$$ $$\alpha$$x2. The distance at which the particle stops :
A
$${\left[ {{{3mv_0^2} \over {2\alpha }}} \right]^{{1 \over 3}}}$$
B
$${\left( {{{2{v_0}} \over {3\alpha }}} \right)^{{1 \over 3}}}$$
C
$${\left( {{{3v_0^2} \over {2\alpha }}} \right)^{{1 \over 2}}}$$
D
$${\left( {{{2v_0^2} \over {3\alpha }}} \right)^{{1 \over 2}}}$$
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