1
JEE Main 2018 (Offline)
MCQ (Single Correct Answer)
+4
-1
A particle is moving in a circular path of radius $$a$$ under the action of an attractive potential $$U = - {k \over {2{r^2}}}$$ Its total energy is:
A
$$- {3 \over 2}{k \over {{a^2}}}$$
B
Zero
C
$$- {k \over {4{a^2}}}$$
D
$${k \over {2{a^2}}}$$
2
JEE Main 2018 (Offline)
MCQ (Single Correct Answer)
+4
-1
A particle is moving with a uniform speed in a circular orbit of radius R in a central force inversely proportional to the nth power of R. If the period of rotation of the particle is T, then :
A
T $$\propto$$ Rn/2
B
T $$\propto$$ R3/2 for any n
C
T $$\propto$$ Rn/2 +1
D
T $$\propto$$ R(n+1)/2
3
JEE Main 2018 (Online) 15th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
A body of mass m is moving in a circular orbit of radius R about a planet of mass M. At some instant, it splits into two equal masses. The first mass moves in a circular orbit of radius $${R \over 2},$$ and the other mass, in a circular orbit of radius $${3R \over 2}$$. The difference between the final and initial total energies is :
A
$$- {{GMm} \over {2R}}$$
B
$$+ {{GMm} \over {6R}}$$
C
$${{GMm} \over {2R}}$$
D
$$- {{GMm} \over {6R}}$$
4
JEE Main 2018 (Online) 15th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Take the mean distance of the moon and the sun from the earth to be $$0.4 \times {10^6}$$ km and $$150 \times {10^6}$$ km respectively. Their masses are $$8 \times {10^{22}}$$ kg and $$2 \times {10^{30}}$$ kg respectively. The radius of the earth is $$6400$$ km. Let $$\Delta {F_1}$$ be the difference in the forces exerted by the moon at the nearest and farthest points on the earth and $$\Delta {F_2}$$ be the difference in the force exerted by the sun at the nearest and farthest points on the earth. Then, the number closest to $${{\Delta {F_1}} \over {\Delta {F_2}}}$$ is :
A
$$2$$
B
$${10^{ - 2}}$$
C
$$0.6$$
D
$$6$$
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