1
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The linear mass density of a thin rod AB of length L varies from A to B as
$$\lambda \left( x \right) = {\lambda _0}\left( {1 + {x \over L}} \right)$$, where x is the distance from A. If M is the mass of the rod then its moment of inertia about an axis passing through A and perpendicular to the rod is :
A
$${2 \over 5}M{L^2}$$
B
$${5 \over {12}}M{L^2}$$
C
$${7 \over {18}}M{L^2}$$
D
$${3 \over 7}M{L^2}$$
2
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Three rods of identical cross-section and lengths are made of three different materials of thermal conductivity K1 , K2 and K3 , respecrtively. They are joined together at their ends to make a long rod (see figure). One end of the long rod is maintained at 100oC and the other at 0oC (see figure). If the joints of the rod are at 70oC and 20oC in steady state and there is no loss of energy from the surface of the rod, the correct relationship between K1 , K2 and K3 is : JEE Main 2020 (Online) 6th September Evening Slot Physics - Heat and Thermodynamics Question 220 English
A
K1 : K3 = 2 : 3,
K2 : K3 = 2 : 5
B
K1 < K2 < K3
C
K1 : K2 = 5 : 2,
K1 : K3 = 3 : 5
D
K1 > K2 > K3
3
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
When a particle of mass m is attached to a vertical spring of spring constant k and released, its motion is described by
y(t) = y0 sin2 $$\omega $$t, where 'y' is measured from the lower end of unstretched spring. Then $$\omega $$ is:
A
$$\sqrt {{g \over {{y_0}}}} $$
B
$${1 \over 2}\sqrt {{g \over {{y_0}}}} $$
C
$$\sqrt {{{2g} \over {{y_0}}}} $$
D
$$\sqrt {{g \over {2{y_0}}}} $$
4
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Two identical electric point dipoles have dipole moments $${\overrightarrow p _1} = p\widehat i$$ and $${\overrightarrow p _2} = - p\widehat i$$ and are held on the x axis at distance '$$a$$' from each other. When released, they move along the x-axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is 'm', their speed when they are infinitely far apart is :
A
$${p \over a}\sqrt {{3 \over {2\pi { \in _0}ma}}} $$
B
$${p \over a}\sqrt {{1 \over {\pi { \in _0}ma}}} $$
C
$${p \over a}\sqrt {{1 \over {2\pi { \in _0}ma}}} $$
D
$${p \over a}\sqrt {{2 \over {\pi { \in _0}ma}}} $$
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