Answer:
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Answer:
<em>The average speed of the train is 45 km/h</em>
Explanation:
<u>Speed</u>
It's defined as the distance (d) per unit of time (t) traveled by an object. The formula is:
![\displaystyle v=\frac{d}{t}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20v%3D%5Cfrac%7Bd%7D%7Bt%7D)
Let's call x the total distance covered by the train. It covered d1=1/3x with a speed of v1=25 km/h. The time taken is calculated solving for t:
![\displaystyle t_1=\frac{d_1}{v_1}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_1%3D%5Cfrac%7Bd_1%7D%7Bv_1%7D)
![\displaystyle t_1=\frac{1/3x}{25}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_1%3D%5Cfrac%7B1%2F3x%7D%7B25%7D)
![\displaystyle t_1=\frac{x}{75}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_1%3D%5Cfrac%7Bx%7D%7B75%7D)
Now the rest of the distance:
d2 = x - 1/3x = 2/3x
Was covered at v2=75 km/h. Thus the time taken is:
![\displaystyle t_2=\frac{d_2}{v_2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_2%3D%5Cfrac%7Bd_2%7D%7Bv_2%7D)
![\displaystyle t_2=\frac{2/3x}{75}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_2%3D%5Cfrac%7B2%2F3x%7D%7B75%7D)
![\displaystyle t_2=\frac{2x}{225}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_2%3D%5Cfrac%7B2x%7D%7B225%7D)
The total time is:
![\displaystyle t_t=\frac{x}{75}+\frac{2x}{225}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_t%3D%5Cfrac%7Bx%7D%7B75%7D%2B%5Cfrac%7B2x%7D%7B225%7D)
![\displaystyle t_t=\frac{3x}{225}+\frac{2x}{225}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_t%3D%5Cfrac%7B3x%7D%7B225%7D%2B%5Cfrac%7B2x%7D%7B225%7D)
![\displaystyle t_t=\frac{5x}{225}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_t%3D%5Cfrac%7B5x%7D%7B225%7D)
Simplifying:
![\displaystyle t_t=\frac{x}{45}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20t_t%3D%5Cfrac%7Bx%7D%7B45%7D)
The average speed is the total distance divided by the total time:
![\displaystyle \bar v=\frac{x}{\frac{x}{45}}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cbar%20v%3D%5Cfrac%7Bx%7D%7B%5Cfrac%7Bx%7D%7B45%7D%7D)
Simplifying:
![\boxed{\displaystyle \bar v=45\ km/h}](https://tex.z-dn.net/?f=%5Cboxed%7B%5Cdisplaystyle%20%5Cbar%20v%3D45%5C%20km%2Fh%7D)
The average speed of the train is 45 km/h
Interference if the hardest to remove due to the superposition of the frequencies of the radio waves
Answer:
conduction
Explanation:
Conduction is a method of heat transfer, where two objects exchange heat by touching, but does not contribute to moving heat through earth's atmosphere, because the atmosphere is so sparse it does not transmit heat through conduction effectively. Insulation is not a method of heat transfer.