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butalik [34]
2 years ago
12

You are boiling pasta and absentmindedly grab a copper stirring spoon rather than your wooden spoon. The copper spoon has a 20 m

m × 1.5 mm rectangular cross section, and the distance from the boiling water to your 35∘C hand is 18 cm. How long does it take the spoon to transfer 40 J of energy to your hand?
Physics
1 answer:
11111nata11111 [884]2 years ago
6 0

The spoon to transfer 40 J of energy to your hand is descibed as follows

<u>Explanation:</u>

Given  area of cross section of copper spoon is A = 20mm into 1.5 mm

temperature difference is DT = (100 minus 35) = 65 0C

length of the spoon is l = 18 cm,

amount of heat should be transfer Q = 40 J

coefficient of thermal conductivity of copper k = 400 W by mk

we know that the thermal conductivity is Q by t = k into A into DT by l

t = Q into l by k into A into DT

t = (40 into 0.18) by  \left(400 \times 30 \times 10^{-6} \times 65\right)

t = 9.23 s

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Explanation:

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2 years ago
A satellite, orbiting the earth at the equator at an altitude of 400 km, has an antenna that can be modeled as a 1.76-m-long rod
ivann1987 [24]

Answer:

The inducerd emf is 1.08 V

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When a conducting rod moves in a uniform magnetic field linearly with velocity, v, then the potential difference due to its motion is given by:

e = - l(vec{v}\times \vec{B})

Here, velocity v is perpendicular to the rod

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e = lvB           (1)

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v = \sqrt{\frac{Gm_{E}}{R_{E}} + H}

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R_{E} = 6371\ km = radius of earth

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6 0
2 years ago
1. Describe the methods by which an electric potential develops in primary cells and dry cells.
Andreyy89

Answer:

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a. Increase

b. Decrease

c. Decrease

Since 1 Btu = 0.293 Wh, dividing the given amount of Wh by 0.293 will convert this amount into Btu. Therefore, 0.8 ÷ 0.293 = 2.73 Btu

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Explanation:

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2 years ago
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