Raditionally mangrove forests<span> were viewed as </span>wastelands and unhealthy environments<span>. People therefore reasoned that </span>their<span> removal would improve the health ...</span>
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

Answer:
2.31J
Explanation:
the energy for a spring system is given by:

where
is the spring constant:
and
is the distance stretched from the equilibrium position.
In the first case 
so the energy to stretch the spring 1.81cm is:

and for the second case, the energy to stretch the spring 5.79cm:


so to answer a) we must find the difference between these energies:

Answer:
299.88 kgm²/s
499.758 kgm²/s
Explanation:
R = Radius of merry-go-round = 1.63 m
I = Moment of inertia = 196 kgm²
= Initial angular velocity = 1.53 rad/s
m = Mass of person = 73 kg
v = Velocity = 4.2 m/s
Initial angular momentum is given by

The initial angular momentum of the merry-go-round is 299.88 kgm²/s
Angular momentum is given by

The angular momentum of the person 2 meters before she jumps on the merry-go-round is 499.758 kgm²/s