The top layer of a goose down sleeping bag has a thickness of 5.0 cm and a surface area of 1.0 m2. when the outside temperature
is -20o c, a body loses 20 cal/hr by heat conduction through the bag (which remains 35o c inside). assuming that a person is sleeping on an insulated pad that prevent heat loss to the ground, find the thermal conductivity of the goose down.
1 answer:
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Explanation:
Given that,
Radius of circular path, r = 5 m
Centripetal acceleration,
(a) Let v is the astronaut’s speed. The formula for the centripetal acceleration is given by :
v = 18.5 m/s
(b) Let T denotes the time period. It is given by :
T = 1.69 s
Let N is the number of revolutions. So,
So, the number of revolutions per minute is 35.5
(c) T = 1.69 seconds
Hence, this is the required solution.
Answer:
Ek = 1705.28 [J]
Explanation:
In order to solve this problem, we must remember that kinetic energy can be calculated by means of the following equation.
where:
m = mass [kg]
v = velocity [m/s]
Ek = kinetic energy [J] (Units of Joules)
<u>For the person running</u>
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<u>For the bullet</u>
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The difference in Kinetic energy is equal to:
Ek = 2025 - 319.72
Ek = 1705.28 [J]
Answer:
Explanation:
In the decibel scale , intensity of sound changes logarithmically as follows
Value in decibel scale , the value of I₀ = 10⁻¹² W /m².
Putting the values
W/m²
Similarly for 54 dB sound intensity can be given as follows
I = 10⁻¹² x
W / m²
For intensity of sound the relation is as follows
I = 2π²υ²A²ρc where υ is frequency , A is amplitude , ρ is density of air and c is velocity of sound .
Putting the given values for 71 dB
= 2π² x 504²xA²x 1.21 x 346
A² = 60.03 x 10⁻¹⁶
A = 7.74 x 10⁻⁸ m
For 54 dB sound
= 2π² x 504²xA²x 1.21 x 346
A² = 1.1978 x 10⁻¹⁶
A = 1.1 x 10⁻⁸ m