Thermodynamics conceptual questions along with solutions

Questions

1. A rod of length L having coefficient of Linear expansion ? is lying freely on the floor.it is heated so that temperature changes by ?T .Find the longitudinal strain developed in the rod
a. 0
b. ΔT
c. -ΔT
d. none of the above

2.if a is coefficient of Linear expansion,b coefficient of areal expansion,c coefficient of Volume expansion.Which of the following is true
a. b=2a
b. c=3a
c. b=3a
d. a=2b

3.which is of them is not used as the measurable properties in thermometer?
a.Resistance of platinum ire
b.Constant volume of gas
c. Constant pressure of gas
d.None of the above

4.when a solid metallic sphere is heated.the largest percentage increase occurs in its
a.Diameter
b. Surface area
c. Volume
d. density

5.the density of the liquid depends upon
a. Nature of the liquid
b. Temperature of the liquid
c. Volume of the liquid
d. Mass of the liquid



6. A metallic sphere has a cavity of diameter D at its center.If the sphere is heated,the diameter of the . cavity will
a. Decrease
b. Increase
c. Remain unchanged
d. none of the above

7.A metallic circular disc having a circular hole at its center rotates about it axis passing through the center and perpendicular to it plane.when the disc is heated
a. Its speed will decrease
b. Diameter will increase
c. Moment of inertia will increase
d. its speed will increase

Solutions

1. (a)
There was no restriction for it expansion.So no tensile or compressive force developed.Longitudinal strains happens only when tensile or compressive force developed in the rod.So answer a
2.(c)
3.(d)
4.(c)
5. (a),(b)
6.(b)
7.(a),(c)
Due to thermal expansion,the diameter of the disc as well of the hole will increase.therefore the moment of inertia will increase resulting in a increase in the angular speed.



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