Answer:
GIVEN
u is 40m/s and v=60m/s
time is 4s
therefore acceleration =60-40/4
=20/4=5m/s^2
b)next 2 sec=70m/s
Answer:
36 minutes
Explanation:
Distance= Time*Speed
Let time taken to go to city be x hours, therefore, time to travel back is (2-x) hours
The distance to and from the city are equal hence
15x=35(2-x)
15x=70-35x
50x=70 hence x=70/50=1.4 hours
Time to drive home will be 2-x=2-1.4=0.6 hours
0.6*60=36 minutes
Therefore, time to travel back home is 36 minutes
Answer:
Therefore,
The frequency heard by the engineer on train 1

Explanation:
Given:
Two trains on separate tracks move toward each other
For Train 1 Velocity of the observer,

For Train 2 Velocity of the Source,

Frequency of Source,

To Find:
Frequency of Observer,
(frequency heard by the engineer on train 1)
Solution:
Here we can use the Doppler effect equation to calculate both the velocity of the source
and observer
, the original frequency of the sound waves
and the observed frequency of the sound waves
,
The Equation is

Where,
v = velocity of sound in air = 343 m/s
Substituting the values we get

Therefore,
The frequency heard by the engineer on train 1
