JEE · NEET Previous Year Question

A pendulum clock lose 12 s a day if the temperature is 40°C and gains 4 s a day if the temperature is 20°C. The temperature at which the clock will show correct time, and the co-efficient of linear expansion (α) of the metal of the pendulum shaft are respectively:

Topic: NEET PYQ

Answer: D. Full step-by-step solution below.

  1. A60°C; α = 1.85 × /°C
  2. B30°C; α = 1.85 × /°C
  3. C55°C; α = 1.85 × /°C
  4. D25°C; α = 1.85 × /°C

Correct answer: D

Solution

(d) α (40 – T) ...(i)
α (20 – T) ...(ii)
from equation (i) and (ii)
–3 =
– 60 + 3T = 40 – T
4T = 100
T = 25
from equation (ii)
α (20 – 25)
× α × 5
α = = 1.85 × /°C

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