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3 years ago

Jenna can run 9 km in 1 hour. If she runs at that speed for 30 minutes, how far will she go? *

Physics

1 answer:

crimeas [40]3 years ago

5 0

Answer:

4.5 km / 450 m

Explanation:

1 hour = 9 km

or, 60 min = 9km

or, 60/2 min = 9/2 km

■ 30 min = 4.5 km

heart plzz and brainliest answer as well

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Explanation:

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3 years ago

The density of mobile electrons in copper metal is 8.4 1028 m-3. Suppose that i = 4.6 1018 electrons/s are drifting through a co

Vesna [10]

Answer:

The time is 106.7 minute.

Explanation:

Given that,

Density $= 8.4\times10^{28}\ m^3$

Current $i = 4.6\times10^{18}\ electron/s$

Diameter of wire = 1.2 mm

Length = 31 cm

We need to calculate the drift velocity

Using formula of drift velocity

$v_{d}=\dfrac{I}{neA}$

$v_{d}=\dfrac{Ne}{tne\times\pi r^2}$

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$v_{d}=\dfrac{4.6\times10^{18}}{8.4\times10^{28}\times\pi\times(0.6\times10^{-3})^2}$

$v_{d}=4.842\times10^{-5}\ m/s$

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Using formula for time

$v_{d}=\dfrac{l}{t}$

$t=\dfrac{l}{v_{d}}$

Where, l = length

$v_{d}$ = drift velocity

Put the value into the formula

$t=\dfrac{31\times10^{-2}}{4.842\times10^{-5}}$

$t=6402.31\ sec$

$t=106.7\ minute$

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3 years ago

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C) alpha radiation seems to be the answer

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2 years ago

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Answer:

D 10.2

Explanation:

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3 years ago

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3 years ago