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Tanya [424]
3 years ago
7

A student walks 4 km in 30 minutes. What is the student’s average speed in km/h? Be sure to include your units. Please help!!!!!

Physics
1 answer:
VladimirAG [237]3 years ago
8 0
4 km in 30 min then 8 km in 60min or an hr. so 8km/hr.
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One end of an insulated metal rod is maintained at 100 ∘C and the other end is maintained at 0.00∘C by ice–water mixture. The ro
Hitman42 [59]

Answer:

153.0815W/m.K

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Heat transferred in phase is changed is expressed as:

Q=\pm mL (m-mass, Q-heat, L-Latent heat of phase change)

Latent heat is the heat required to change the phase of 1kg of the material.

#The rate of heat flow(by conduction)  per unit time:

H=\frac{\bigtriangleup Q}{\bigtriangleup t}=kA\frac{T_H-T_C}{L}\\\\L_f=334\times10^3J/kj\\\\H_{ice}=\frac{Q_{ice}}{t}=\frac{m_{ice}L_f}{t} #Heat flowing through melting ice.

H_{ice}=\frac{5.0\times10^-^3kg)334\times10^3J/kg)}{10\times60s}\\\\=2.7833J/s

To solve for k:

H=\frac{\bigtriangleup Q }{\bigtriangleup t}\\\\=kA\frac{T_H-T_C}{L}H=\frac{\bigtriangleup Q }{\bigtriangleup t}\\\\=kA\frac{T_H-T_C}{L}H=\frac{\bigtriangleup Q }{\bigtriangleup t}\\\\=kA\frac{T_H-T_C}{L}\\\\k=\frac{H}{A\frac{T_H-T_C}{L}}=\frac{HL}{A(T_H-T_C)}

=\frac{(2.7833J/s\times 0.55)}{1.00\times10^-^4m^2\times 100K}\\\\=153.0815W/m.K

The thermal conductivity k of the metal is 153.0815W/m.K

8 0
3 years ago
3. Does the Sun's light that reaches Earth produce a true continuous rainbow? If not, what colors
dangina [55]

Answer:

when there is no water in the atmosphere or when no drops are formed there is no rainbow..

he hydrogen transition lines would be missing in the visible range,  the RED region

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The sunlight that reaches the Earth is scattered by the atmosphere and radiated, as the atmosphere has mainly nitrogen, the radiated light is blue, this light does not produce a rainbow.

The sunlight must reach a drop of water that disperses the colors according to the refractive index of the water and in this way produces a rainbow, so when there is no water in the atmosphere or when no drops are formed there is no rainbow..

If the atmosphere were composed of Hydrogen, the hydrogen transition lines would be missing in the visible range, this corresponds to the so-called Balmer series and they are in the RED light region.

8 0
4 years ago
Which wave interaction is responsible for echoes?
IrinaVladis [17]

Answer:Reflection

Explanation:

5 0
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