1
JEE Main 2021 (Online) 25th July Evening Shift
+4
-1
A force $$\overrightarrow F = (40\widehat i + 10\widehat j)N$$ acts on a body of mass 5 kg. If the body starts from rest, its position vector $$\overrightarrow r$$ at time t = 10 s, will be :
A
$$(100\widehat i + 400\widehat j)m$$
B
$$(100\widehat i + 100\widehat j)m$$
C
$$(400\widehat i + 100\widehat j)m$$
D
$$(400\widehat i + 400\widehat j)m$$
2
JEE Main 2021 (Online) 20th July Evening Shift
+4
-1
The length of a metal wire is l1, when the tension in it is T1 and is l2 when the tension is T2. The natural length of the wire is :
A
$$\sqrt {{l_1}{l_2}}$$
B
$${{{l_1}{T_2} - {l_2}{T_1}} \over {{T_2} - {T_1}}}$$
C
$${{{l_1}{T_2} + {l_2}{T_1}} \over {{T_2} + {T_1}}}$$
D
$${{{l_1} + {l_2}} \over 2}$$
3
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
4
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
$${F \over m}\cos \theta - {\mu _K}\left( {g + {F \over m}\sin \theta } \right)$$
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