NEET UG PHYSICS MCQ: THERMAL PROPERTIES OF MATTER

1 Medium

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Analyzing +4 | -1

30.0 \mathrm{~cm}

long metal rod expands by

0.0650 \mathrm{~cm}

when its temperature is raised from

0^{\circ} \mathrm{C}

100^{\circ} \mathrm{C}

. A second rod of different metal and of the same length expands by

0.0350 \mathrm{~cm}

for the same rise in temperature. A third composite rod, also

30.0 \mathrm{~cm}

long, is made-up of pieces of each of the above metals placed end to end and expands by

0.0580 \mathrm{~cm}

when temperature is increased from

0^{\circ} \mathrm{C}

100^{\circ} \mathrm{C}

. Find the length of the smaller portion of the composite bar (in

\mathrm{cm}

) at

0^{\circ} \mathrm{C}

View answer and explanation

Correct option: A

Option A (7 cm) is correct. It is found by setting up equations for the total expansion of the composite rod based on the individual expansions and solving for the length of the smaller portion.

More Questions from THERMAL PROPERTIES OF MATTER

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Four identical calorimeters painted in different colours, are heated to same temperature and then allowed to cool in vacuum. Which will cool fastest? An ice cube of dimensions

60 \mathrm{~cm} \times 50 \mathrm{~cm} \times 20 \mathrm{~cm}

is placed in an insulation box of wall thickness

1 \mathrm{~cm}

. The box keeping the ice cube at

0^{\circ} \mathrm{C}

of temperature is brought to a room of temperature

40^{\circ} \mathrm{C}

. The rate of melting of ice is approximately.

(Latent heat of fusion of ice is

3.4 \times 10^5 \mathrm{~J} \mathrm{~kg}^{-1}

and thermal conducting of insulation wall is

\left. {0.05{\text{W}}{{\text{m}}^{ - 1}}^\circ {{\text{C}}^{ - 1}}} \right)

A black body radiates heat energy at the rate of

2 \times 10^5 \mathrm{~J} / \mathrm{sm}^2

at temp. of

127^{\circ} \mathrm{C}

. The temp of black body at which rate becomes

32 \times 10^5 \mathrm{~J} / \mathrm{s}-\mathrm{m}^2

is: The amount of radiation emitted by a perfectly black body is proportional to Amount of heat required to raise the temperature of a body through 1K is called its If Poisson’s ratio

\sigma

+ \frac{1}{2}

for a material, then the material is