Question

The coefficient of linear expansion of ordinary glass is three times that of Pyrex glass. An ordinary glass rod and a Pyrex glass rod of equal lengths at room temperature are dropped into boiling water. The change in length of the ordinary glass rod will be ___________ the change in length of the Pyrex glass rod. a. 1/3

b. 3 times
c. equal to
d. 1/9
e. 9 times

Answer 1

b. 3 times

Step-by-step explanation:

Lets take

Coefficient for ordinary glass = α₁

Coefficient for pyrex glass = α₂

Given that α₁ = 3 α₂

Initial length of both glasses are equal = L

Change in the temperature is also same .= ΔT

We know that change in the length given as

ΔL = L α ΔT

Therefore

`(\Delta L_1)/(\Delta L_2)=(L\alpha_1\Delta T)/(L\alpha_2\Delta T)`

`(\Delta L_1)/(\Delta L_2)=(3\alpha_2)/(\alpha_2)`

ΔL₁ = 3ΔL₂

Therefore change in the length of original glass is three time of pyrex glass.

b. 3 times