Volume of a cube of side l and volume of a sphere of radius r are equal. Both the cube and the sphere are solid and of same material. They are being cast. The ratio of the solidification time of the cube to the same of the sphere is
(4π/6)³ × (r/l)⁶
(4π/6) × (r/l)²
(4π/6)² × (r/l)³
(4π/6)² × (r/l)⁴
Correct Answer :
D. (4π/6)² × (r/l)⁴
Related Questions
A dense structure of a grinding wheel is used for
Hard materials
Brittle materials
Finishing cuts
All of these
A drill considered as a cutting tool having zero rake, is known as a
Flat drill
Straight fluted drill
Parallel shank twist drill
Tapered shank twist drill
The lip angle is the angle
Between the tool face and the ground end surface of flank
Made by the face of the tool and the plane parallel to the base of the cutting tool
Between the face of the tool and a line tangent to the machined surface at the cutting point
None of the above
The top and sides of the table of a shaper usually have
L-type slots
T-type slots
I-type slots
Any one of these
Which of the following statement is correct regarding grinding of high carbon steel?
Grinding at high speed results in the reduction of chip thickness and cutting forces per grit.
Aluminium oxide wheels are employed.
The grinding wheel has to be of open structure.
All of the above
The guideways are of
Flat type
V-type
Dovetail type
Any one of these
In order to prevent tool from rubbing the work _________ on tools are provided.
Rake angles
Relief angles
Face angles
None of these
Which type of motor is not used in axis or spindle drives of CNC machine tools?
Induction motor
DC servo motor
Stepper motor
Linear servo motor
Hardness of steel greatly improves with
Annealing
Cyaniding
Normalizing
Tempering
Grinding wheels should be tested for balance
Only at the time of manufacture
Before starting the grinding operation
At the end of grinding operation
Occasionally
A grinding wheel becomes glazed (i.e. cutting edge takes a glasslike appearance) due to
Wear of bond
Breaking of abrasive grains
Wear of abrasive grains
Cracks on grinding wheel
Soft materials can not be economically ground due to
High temperature involved
Frequent wheel clogging
Rapid wheel wear
Low work piece stiffness
In determining the various forces on the chip, Merchant assumed that the
Cutting edge of the tool is sharp and it does not make any flank contact with the workpiece
Only continuous chip without built-up-edge is produced
Cutting velocity remains constant
All of the above
Low helix angle drills are preferred for drilling holes in
Plastics
Copper
Cast steel
Carbon steel
In drilling Bakelite and fibrous plastics, the point angle of a drill is
90°
118°
135°
150°
Segmental chips are formed during machining
Mild steel
Cast iron
High speed steel
High carbon steel
Which of the following statement is wrong as regard to down milling?
It can not be used on old machines due to backlash between the feed screw of the table and the nut.
The chips are disposed off easily and do not interfere with the cutting.
The surface milled appears to be slightly wavy.
The coolant can be poured directly at the cutting zone where the cutting force is maximum.
When 3-2-1 principle is used to support and locate a three dimensional work-piece during machining, the number of degrees of freedom that are restricted is
7
8
9
10
Which of the following statement is correct in regard to centreless grinding?
The workpiece is supported throughout its entire length as grinding takes place.
It is a continuous process and adopted for production work.
It requires no holding device for the work.
All of the above
The point angle of a drill, for drilling stainless steel, is
90°
118°
135°
150°
The crystal structure of austenite is
Body centred cubic
Base centred cubic
Hexagonal closed packed
Body centred tetragonal
In ultrasonic machining, tool is made of
Tungsten carbide
Brass or copper
Diamond
Stainless steel
The taper on the lathe spindle is
1 in 10
1 in 15
1 in 20
1 in 30
What type of fusion welding process is used for welding sheet metals of all engineering metals (except Cu, Ag) in automobile and air craft industries, pipe and tubing production?
Thermit welding
Electroslag welding
Resistance welding
Submerged arc welding
The cutting speed is maximum while machining __________ with a high speed steel tool.
Cast iron
Mild steel
Brass
Aluminium
A fixture is defined as a device which
Holds and locates a workpiece and guides and controls one or more cutting tools
Holds and locates a workpiece during an inspection or for a manufacturing operation
Is used to check the accuracy of workpiece
All of the above
In a shaper, the metal is removed during
Forward stroke
Return stroke
Both the forward and return strokes
Neither the forward nor the return stroke
The type of tool used on milling machine and broaching machine is
Single point cutting tool
Two point cutting tool
Three point cutting tool
Multipoint cutting tool
When the temperature of a solid metal increases,
Strength of the metal decreases but ductility increases
Both strength and ductility of the metal decreases
Both strength and ductility of the metal increases
Strength of the metal increases but ductility decreases
What is the type of joining process called, where the parts to be welded are kept in contact and rotated relative to each other and axial pressure is applied when the desired temperature is obtained?
Ultrasonic welding
Forge welding
Electron beam welding
Friction welding