Class XI

A brass wire 1.8 m long at 27 ∘∘C is held taut with little tension between two rigid supports. If the wire is cooled to a temperature of –39 ∘∘C, what is the tension developed in the wire, if its diameter is 2.0 mm? Co-efficient of linear expansion of brass = 2.0 ×× 10−510−5 K−1K−1; Young’s modulus of brass = 0.91 ×× 10111011 Pa.
  1. 3.4 x 102102 N
  2. 3.8 x 102102 N
  3. 3.2 x 102102 N
  4. 3.6 x 102102 N
A parrot is in a wire case, which is hanging from a spring balance. Initially the parrot sits in the cage and in the second instant the parrot flies inside the cage
  1. None of the above
  2. the reading will remain unchanged
  3. the reading of the balance will be lesser when the parrot flies in the cage
  4. the reading of the balance will be greater when the parrot flies in the cage
A 0.050 0-kg ingot of metal is heated to 200.0∘∘C and then dropped into a beaker containing 0.400 kg of water initially at 20.0∘∘C. If the final equilibrium temperature of the mixed system is 22.4∘∘C, find the specific heat of the metal.
  1. 4.83 J/kg∘∘C
  2. 4.63 J/kg. ∘∘C
  3. 4.73 J/kg. ∘∘C
  4. 4.53 J/kg. ∘∘C
A brass spring has a spring constant k. When the spring is heated, the spring constant will
  1. decrease
  2. remain the same
  3. increase
  4. increase, then decrease
The coefficient of volume expansion of glycerin is 49 ×× 10−510−5 K–1. What is the fractional change in its density for a 30 ∘∘C rise in temperature?
  1. 0.0107
  2. 0.0157
  3. 0.0127
  4. 0.0147
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