Physics - Properties of Bulk Matter

Question - 1

A body of mass m=10 kg is attached to a wire of length 0.3m. The maximum angular velocity with which it can be rotated in a horizontal circle is (Breaking stress of wire = \(4.8\)\(\times\)\({ 10 }^{ 7 }\) \({ N/m }^{ 2 }\)and area of cross-section of wire =\({ 10 }^{ -6 }{ m }^{ 2 }\))

  • A 4 rad/s
  • B 8 rad/s
  • C 1 rad/s
  • D 2 rad/s

Question - 2

The breaking stress for a copper wire is \(2.2\times { 10 }^{ 8 }{ Nm }^{ -2 }\)The maximum length of the copper wire which when suspended vertically for which the wire will not break under its own weight, will be (Density of copper = \({ 8.8\times 10 }^{ 3 }{ kgm }^{ -3 }\))

  • A 25000 m
  • B 2500 m
  • C 250 m
  • D 25 m

Question - 3

A mild steel wire of length 2L and cross-sectional area A is stretched, well within elastic limit, horizontally between two pillars sa shown in figure. A mass m in suspended from the mid -point of the wire strain in the wire is   

  • A \(\frac { { X }^{ 2 } }{ { 2L }^{ 2 } } \)
  • B \(\frac { X }{ L } \)
  • C \(\frac { { X }^{ 2 } }{ L } \)
  • D \(\frac { { X }^{ 2 } }{ 2L } \)

Question - 4

A load of 25 kg-wt is applied on a wire of diameter 0.4 cm, then the young's modulus of wire will be 

  • A \({ 9.75\times 10 }^{ 9 }dyne\quad { cm }^{ -2 }\)
  • B \({ 9.75\times 10 }^{ 9 }N\quad { m }^{ -2 }\)
  • C \({ 5.79\times 10 }^{ 8 }dyne\quad { cm }^{ -2 }\)
  • D \({ 5.79\times 10 }^{ 8 }N\quad { m }^{ -2 }\)

Question - 5

A wire is stretched through 1 mm by certain load. The extention produced in the wire of same materal with double the lengh and double the radius will be 

  • A 4 mm
  • B 3 mm
  • C 1 mm
  • D 0.5 mm

Question - 6

A 10 m long thick rubber pipe is suspended from one of its ends. The extension produced produced pipe under its own weight will be (Y = \({ 5\times 10 }^{ 6 }N\quad { m }^{ -2 }\) and density of rubber = 1500kg \({ m }^{ -3 }\) )

  • A 1.5m
  • B 0.15m
  • C 0.015m
  • D 0.0015m

Question - 7

The volume of water changes from 100 L to 99.5 L under a pressure of 100 atmosphere. The bulk modulus of water will be 

  • A \({ 1.013\times 10 }^{ 5\quad  }{ Nm }^{ -2 }\)
  • B \({ 1.013\times 10 }^{ 9 }\quad { Nm }^{ -2 }\)
  • C \({ 2.026\times 10 }^{ 5 }\quad { Nm }^{ -2 }\)
  • D \({ 2.026\times 10 }^{ 9 }\quad { Nm }^{ -2 }\)

Question - 8

A copper wire (\({ Y=1\times 10 }^{ 11 }\quad { Nm }^{ -2 }\)) of length 6 m and a steel wire (\({ Y=2\times 10 }^{ 11 }\quad { Nm }^{ -2 }\)) of length 4 m each of cross-section \({ 10 }^{ -5 }\)\({ m }^{ 2 }\) are fastened end to end and stretched by a tension of 100 N. The elongation produced in the copper wire is 

  • A 0.2 mm
  • B 0.4 mm
  • C 0.6 mm 
  • D 0.8 mm 

Question - 9

A rigid bar of mass M is supported symmetrically by three wires each of length l. Those at each end are of copper and the middle one is of iron. The ratio of their diameters, it each is to have the same tension is equal to 

  • A \({ Y }_{ copper }/{ Y }_{ iron }\)
  • B \(\sqrt { \frac { { Y }_{ iron } }{ { Y }_{ copper } } } \)
  • C \(\frac { { Y }^{ 2\quad }_{ iron } }{ { Y }^{ 2 }_{ copper } } \)
  • D \(\frac { { Y }_{ iron } }{ { Y }_{ copper } } \)

Question - 10

A solid cylindrical rod of radius 3mm gets depressed under the influence of a load through 8mm. The depression produced in an identical hollow rod with outer and inner radii of 4mm and 2mm respectively, will be 

  • A 2.7mm
  • B 1.9mm
  • C 3.2mm
  • D 7.7mm
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