1
JEE Main 2018 (Online) 16th April Morning Slot
+4
-1 Two particles of the same mass m are moving in circular orbits because of force, given by $$F\left( r \right) = {{ - 16} \over r} - {r^3}$$

The first particle is at a distance r = 1, and the second, at r = 4. The best estimate for the ratio of kinetic energies of the first and the second particle is closest to :
A
$$6 \times {10^{ - 2}}$$
B
$$3 \times {10^{ - 3}}$$
C
$${10^{ - 1}}$$
D
$$6 \times {10^{ 2}}$$
2
JEE Main 2018 (Online) 16th April Morning Slot
+4
-1 A body of mass m starts moving from rest along x-axis so that its velocity varies as $$\upsilon = a\sqrt s$$ where a is a constant and s is the distance covered by the body. The total work done by all the forces acting on the body in the first t seconds after the start of the motion is :
A
$${1 \over 8}\,$$ m a4 t2
B
8 m a4 t2
C
4 m a4 t2
D
$${1 \over 4}\,$$ m a4 t2
3
JEE Main 2017 (Online) 8th April Morning Slot
+4
-1 An object is dropped from a height h from the ground. Every time it hits the ground it looses 50% of its kinetic energy. The total distance covered as t $$\to$$ $$\infty$$ is :
A
3h
B
$$\infty$$
C
$${5 \over 3}$$h
D
$${8 \over 3}$$h
4
JEE Main 2017 (Offline)
+4
-1 A body of mass m = 10–2 kg is moving in a medium and experiences a frictional force F = –kv2. Its initial speed is v0 = 10 ms–1. If, after 10 s, its energy is $${1 \over 8}mv_0^2$$, the value of k will be:
A
10-1 kg m-1 s-1
B
10-3 kg m-1
C
10-3 kg s-1
D
10-4 kg m-1
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