Question

A barometer with brass scale correct at 0°C reads 70cm so mercury on a day when the air temperature is 40°C the correct reading at 0°C is (cofficient of real expansion of mercury is 0.00018/°C and the coefficient of linear expansion of brass is 0.000018/°C

Answer 1

Thus the weight is Ho = 69.97 g

Explanation:

We are given that:

• Temperature = 0°C
• Scale reading = 70 cm
• Air temperature = 70°C
• Coefficient of real expansion of mercury = 0.00018/°C

Solution:

Ho = H  [ 1 - ( γ - α ) Δt ]

Ho = 70 [  1 - (0.00018 - 0.00018 g )(-40) ]

Ho = 70 [ 1 - 0.00036]

ho = 70 x  0.99964

Ho = 69.97 g