641. The centre of gravity of a uniform lamina lies at
A.The centre of heavy portion
B.The bottom surface
C.The mid point of its axis
D.All of the above

642. Centre of gravity of a solid cone lies on the axis at the height
A.One-fourth of the total height above base
B.One-third of the total height above base
C.One-half of the total height above base
D.Three-eighth of the total height above the base

643. Centre of percussion is
A.The point of C.G.
B.The point of metacentre
C.The point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis
D.Point of suspension

644. Centre of gravity of a thin hollow cone lies on the axis at a height of
A.One-fourth of the total height above base
B.One-third of the total height above base
C.One-half of the total height above base
D.Three-eighth of the total height above the base

645. The centre of percussion of the homogeneous rod of length L suspended at the top will be
A.L/2
B.L/3
C.3L/4
D.2L/3

646. The units of moment of inertia of mass are
A.Kg-m2
B.m4
C.Kg/m2
D.Kg/m

647. The units of moment of inertia of area are
A.Kg-m2
B.m4
C.Kg/m2
D.Kg/m

A.Compression or tension
B.Buckling or shear
C.Shear or tension
D.All of the above

649. A heavy string attached at two ends at same horizontal level and when central dip is very small approaches the following curve
A.Catenary
B.Parabola
C.Hyperbola
D.Elliptical

650. A trolley wire weighs 1.2 kg per metre length. The ends of the wire are attached to two poles 20 meters apart. If the horizontal tension is 1500 kg find the dip in the middle of the span
A.2.5 cm
B.3.0 cm
C.4.0 cm
D.5.0 cm

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