Thermal Properties Of Matter

Step 1: Concept
According to Stefan-Boltzmann law, the net loss of energy of a body by radiation is .
Step 2: Conversion
Convert temperatures to Kelvin: . . .
Step 3: Calculation
.
Final Answer: (A)

Step 1: Concept
In equilibrium, the rate of flow of heat entering the junction equals the rate of flow of heat leaving it.
Step 2: Equation
$ $
Final Answer: (C)

Step 1: Understanding the Concept:
The three coefficients of thermal expansion are related: , where , , are linear, area, and volume expansion coefficients.

Step 2: Detailed Explanation:
Percentage change in radius . Percentage change in volume . Percentage change in density in magnitude. Volume change is radius change, and is numerically the largest positive change.

Step 3: Final Answer:
Percentage change is maximum in volume.

Step 1: Understanding the Concept:
, so when R constant.
Step 2: Detailed Explanation:
density
New
Step 3: Final Answer:
New g is .

Step 1: Understanding the Concept:
Sum of distances covered equals tower height.
Step 2: Detailed Explanation:
Let time = t
,


Step 3: Final Answer:
They cross after 2 seconds.

Step 1: Understanding the Concept:
Identify which quantity is dimensionless.
Step 2: Detailed Explanation:
Poisson's ratio = lateral strain/longitudinal strain, hence dimensionless. Phase difference, mechanical equivalent, loudness have units.
Step 3: Final Answer:
Poisson's ratio has no unit.

Step 1: Understanding the Concept:
Relative velocity is vector difference.
Step 2: Detailed Explanation:

Step 3: Final Answer:
Upward speed is 8 m/s.

Step 1: Understanding the Concept:
Orbital speed for a near-Earth satellite is the first cosmic velocity.
Step 2: Detailed Explanation:
Orbital speed ≈ 7.9 km/s, rounded ≈ 8 km/s.
Step 3: Final Answer:
Speed is about 8 km/s.

Step 1: Understanding the Concept:
Different sources produce different spectra types.
Step 2: Detailed Explanation:
Incandescent lamp produces continuous spectrum. Mercury and sodium lamps give line spectra. Polyatomic substances give band spectra.
Step 3: Final Answer:
Incandescent electric lamp produces continuous emission spectrum.