1
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
Consider a drop of rain water having mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 m s$$-$$1. Take 'g' constant with a value 10 m s$$-$$2. The work done by the (i) gravitational force and the (ii) resistive force of air is
A
(i) 1.25 j   (ii) $$-$$8.25 J
B
(i) 100 j   (ii) 8.75 J
C
(i) 10 j   (ii) $$-$$8.75 J
D
(i) $$-$$10 j   (ii) $$-$$8.25 J
2
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
One end of string of length $$l$$ is connected to a particle of mass 'm' and the other end is connected to a small peg on a smooth horizontal table. If the particle moves in circle with speed '$$\upsilon $$', the net force on the particle (directed towards centre) will be (T represents the tension in the string)
A
$$T + {{m{v^2}} \over l}$$
B
$$T - {{m{v^2}} \over l}$$
C
zero
D
$$T$$
3
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
Two astronauts are floating in gravitational free space after having lost contact with their spaceship. The two will
A
move towards each other.
B
move away from each other.
C
will become stationary.
D
keep floating at the same distance between them.
4
NEET 2017
MCQ (Single Correct Answer)
+4
-1
Change Language
Two discs of same moment of inertia rotating about their regular axis passing through centre and perpendicular to the plane of disc with angular velocities $${\omega _1}$$ and $${\omega _2}$$. They are brought into contact face to face coinciding the axis of rotation. The expression for loss of energy during this process is
A
$${1 \over 4}I{\left( {{\omega _1} - {\omega _2}} \right)^2}$$
B
$$I{\left( {{\omega _1} - {\omega _2}} \right)^2}$$
C
$${1 \over 8}I{\left( {{\omega _1} - {\omega _2}} \right)^2}$$
D
$${1 \over 2}I{\left( {{\omega _1} + {\omega _2}} \right)^2}$$