1
NEET 2017
MCQ (Single Correct Answer)
+4
-1
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
Which of the following statements are correct ?

(1)   Centre of mass of a body always coincides with the centre of gravity of the body.

(2)   Centre of mass of a body is the point at which the total gravitational torque on the body is zero.

(3)   A couple on a body produces both translational and rotational motion in a body

(4)   Mechanical advantage greater than one means that small effort can be used to lift a large load.
A
(1) and (2)
B
(2) and (3)
C
(3) and (4)
D
(4)
3
NEET 2017
MCQ (Single Correct Answer)
+4
-1
A rope is wound around a hollow cylinder of mass 3 kg and radius 40 cm. What is the angular acceleration of the cylinder if the rope is pulled with a force of 30 N?
A
0.25 rad s$$-$$2
B
25 rad s$$-$$2
C
5 m s$$-$$2
D
25 m s$$-$$2
4
NEET 2017
MCQ (Single Correct Answer)
+4
-1
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
$${1 \over 2}I{\left( {{\omega _1} + {\omega _2}} \right)^2}$$
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