M.I. of a thin ring (external diameter D, internal diameter d) about an axis perpendicular to the plane of the ring, is
π/64 (D4 + d4)
π/32 (D4 - d4)
π/32 (D4 + d4)
π/32 (D4 × d4)
Correct Answer :
B. π/32 (D4 - d4)
Related Questions
The locus of the instantaneous centre of a moving rigid body, is
Straight line
Involute
Centroid
Spiral
Minimum pull in a suspended cable with supports at two ends is equal to
Horizontal thrust
Support reactions
Resultant of horizontal thrust and support reaction
Half the weight of the cable
Pick up the correct statement from the following. A rubber ball when strikes a wall rebounds but a lead ball of same mass and velocity when strikes the same wall, falls down
Rubber and lead balls undergo equal changes in momentum
Change in momentum suffered by lead ball is less that of rubber ball
Momentum of rubber ball is less than that of lead ball
None of these
The horizontal reaction at the support A of the structure shown in below figure, is
Zero
2 t
3 t
1 t
When a circular wheel rolls on a straight track, then the shape of body centrode and space centrode respectively are
Straight line and parabola
Straight line and circle
Circle and straight line
Circle and parabola
The C.G. of the shaded area of the below figure whose curve OM is a parabola from y-axis, is 
a/4
3a/4
3b/10
3a/10
The angular speed of a car while taking a circular turn of radius 100 m at 36 km/hour, is
0.1 radian/sec
1 radian/sec
100 radian/sec
1000 radian/sec
If a body moves in such a way that its velocity increases by equal amount in equal intervals of time, it is said to be moving with
A uniform retardation
A uniform acceleration
A variable acceleration
A variable retardation
The velocity of a moving body, is
A vector quantity
A scalar quantity
A constant quantity
None of these
The time period of a simple pendulum depends on (i) Mass of suspended particle (ii) Length of the pendulum (iii) Acceleration due to gravity The correct answer is
Only (i)
Both (ii) and (iii)
Both (i) and (iii)
All are correct
The equation of motion of a particle starting from rest along a straight line is x = t3 - 3t2+ 5. The ratio of the accelerations after 5 sec and 3 sec will be
2
3
4
5
The force polygon representing a set of forces in equilibrium is a
Triangle
Open polygon
Closed polygon
Parallelogram
Which of the following is a scalar quantity?
Energy
Momentum
Torque
Impulse
The unit of impulse, is
kg.m/sec
kg.m/sec
kg.m/sec2
kg.m/sec
A force P of 50 N and another force Q of unknown magnitude act at 90° to each other. They are balanced by a force of 130 N. The magnitude of Q is
60 N
80 N
100 N
120 N
The tension in a cable supporting a lift
Is more when the lift is moving downwards
Is less when the lift is moving upwards
Remains constant whether its moves downwards or upwards
Is less when the lift is moving downwards
The product of mass and velocity of a moving a body, is called
Moment
Momentum
Power
Impulse
A marble ball is rolled on a smooth floor of a room to hit a wall. If the time taken by the ball in returning to the point of projection is twice the time taken in reaching the wall, the coefficient of restitution between the ball and the wall, is
0.25
0.50
0.75
1.0
A stone of mass 1 kg is tied to a string of length 1 m and whirled in a horizontal circle at a constant angular speed 5 rad/sec. The tension in the string is,
5 N
10 N
15 N
25 N
A stone is thrown up a slope of inclination 60° to the horizontal. At what angle to the slope must the stone be thrown so as to land as far as possible from the point of projection?
15°
30°
45°
75°
Periodic time of a particle moving with simple harmonic motion is the time taken by the particle for
Half oscillation
Quarter oscillation
Complete oscillation
None of these
On a ladder resting on a rough ground and leaning against a smooth vertical wall, the force of friction acts
Downwards at its upper end
Upwards at its upper end
Perpendicular to the wall at its upper end
Zero at its upper end
The velocity of a body fallen from height h, on reaching the ground is given by
v = 2gh
v = 2gh2
v = √(2gh)
v = 1/√(2gh)
The centre of gravity of a quadrant of a circle lies along its central radius at a distance of
0.2 R
0.4 R
0.3 R
0.6 R
A stone is thrown vertically upwards with a vertical velocity of 49 m/sec. It returns to the ground in
5 sec
8 sec
10 sec
20 sec
A square hole is punched out of a circular lamina, the diagonal of the square being the radius of the circle. If r is the radius of the circle, the C.G. of the remainder from the corner of the square on the circumference will be
[r (π + 0.25)]/(π - 0.5)
[r (π - 0.5)]/(π + 0.25)
[r (π - 0.25)]/(π - 0.5)
[r (π + 0.25)]/(π + 0.5)
The ends of a string weighing w/metre are attached to two points at the same horizontal level. If the central dip is very small, the horizontal tension of the string throughout is
wl/4d
wl²/4d
wl²/8d
wl²/16d
Pick up the incorrect statement from the following. In case of suspension bridge due to rise in temperature,
Dip of the cable increases
Length of the cable increases
Dip of the cable decreases
None of these
If the resultant of two forces has the same magnitude as either of the force, then the angle between the two forces is
30°
45°
60°
120°
One Joule is equivalent to
9.81 Newton metre
1 Newton metre
1 kg wt metre
1 dyne metre