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Q:

# A stone floor feels cold to the bare feet but a carpet on the same floor feels warm. This is because

 A) the floor and carpet are at different temperatures B) the stone conveys the heat away from the feet more rapidly than the carpet C) the carpet is a better conductor of heat than the stone D) the human body maintains a constant temperature

Answer:   B) the stone conveys the heat away from the feet more rapidly than the carpet

Explanation:

Both the floor and the carpet have the same temperature as both are exposed to the same atmosphere. But the former conducts away the heat from the feet better than the carpet as the latter is a non-conductor. So the feet losing more heat, the floor appears cooler to the feet.

Subject: Physics
Q:

Two metallic plate of equal thickness and coefficient thermal conductivity K1 and K2 put together face to face. A common plate is constructed. What is equivalent K?

 A) K1k2/k1+k2 B) 2k1k2/k1+k2 C) K1+k2/k1k2 D) None

Answer & Explanation Answer: B) 2k1k2/k1+k2

Explanation:

We know that,

The equivalent K =  $\fn_jvn \small \frac{L1+L2}{\frac{L1}{K1}+\frac{L2}{K2}}$

where L1 & L2 are plate1 & Plate2 thicknesses, K1 & K2 are coefficient thermal conductivity of plate1 & Plate2 respectively.

But here L1 = L2 = L (say)

Then K = L+L/(L/K1 + L/K2)  =  $\fn_jvn \small \frac{2K1K2}{K1+K2}$

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4 86
Q:

"Light years" is the unit of _____?

 A) Acceleration B) Distance C) Light Intensity D) Weight

Answer & Explanation Answer: B) Distance

Explanation:

A Light-year is a distance that light travels in the vacuum in one Julian year (365.25 days).

The light-year is a unit of length used to express astronomical distances. It is about 9.5 trillion kilometers or 5.9 trillion miles.

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6 173
Q:

"The Law of Kepler" is related with which among the following ?

 A) Planetary Motion B) Law of Conservation of energy C) Law of Gravitation D) None

Answer & Explanation Answer: A) Planetary Motion

Explanation:

Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.

• Kepler’s three laws of planetary motion can be stated as follows:

(1) All planets move about the Sun in elliptical orbits, having the Sun as one of the foci.

(2) A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time.

(3) The squares of the sidereal periods (of revolution) of the planets are directly proportional to the cubes of their mean distances from the Sun.

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10 135
Q:

The Hydraulic Break works on the principle of _____ ?

 A) Pascal's Law B) Boyle's law C) Coulomb's law D) Bernouli's law

Answer & Explanation Answer: A) Pascal's Law

Explanation:
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6 298
Q:

What is the full form of "RADAR" ?

 A) Radio Detecting and Ranging B) Region Device and Ranging C) Radio Detect and Rangs D) Radio Device and Ranging

Answer & Explanation Answer: A) Radio Detecting and Ranging

Explanation:
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