Answer:
37.545 m/s
Explanation:
f' = Actual frequency of horn = 269 Hz
f = Observed frequency of horn = 290 Hz
v = Speed of sound in air = 343 m/s
= Speed of second train = 13.7 m/s
= Speed of first train
From Doppler effect we have

The speed of the first train is 37.545 m/s
It only occurs when there is an electric current
I think it's wavelength
Hope I helped.
Answer:
There are total eight planets in the solar system and the average distance from the sun to each planet in increasing order is given below.
Explanation:
The average distance from the sun is listed below in increasing order.
1. Mercury - It is the most closet planet to Sun, 57 million km
2. Venus - 108 million km
3. Earth - 150 million km
4. Mars - 228 million km
5. Jupiter - 779 million km
6. Saturn - 1.43 billion km
7. Uranus - 2.88 billion km
8. Neptun - It is the most farthest from the Sun, 4.50 billion km
So impulse is a change in momentum.
Mass*(final velocity - initial velocity)
I dont think you will be able to find the average force with the given info because you need to know the time it takes for the car to slow down.