Answer:
<u>because of the doppler effect</u>
Explanation:
<em>Remember</em>, the doppler effect refers to the changes in sound (frequency of sound) observed by a person who is in a position relative to the wave source.
In this example, we notice as the train comes closer to the boy, the sound becomes louder also increasing the pitch slightly, the doppler effect sets in when the train passes the boy because the boy notices a decrease in the pitch of the moving train.
We learn from the change in the observed sound of the train that the frequency of the sound is determined by the distance of the observer from the wave source.
In other words, the closer the source of the sound to the observer; the faster it travels to the observer, however, the farther it is; the lesser it is; the greater the sound heard.
Answer:
Therefore the surface area of the balloon is increased at 4 cm³/s.
Explanation:
The balloon is being filled with air at a rate of 10 cm³/s
It means the volume of the balloon is increased at a rate 10 cm³/s.
i.e 
Consider r be the radius of the balloon.
The volume of of a sphere is

Differentiate with respect to t



The surface of area of the balloon is(S) = 

Differentiate with respect to t


Putting the value of


Given that r = 5 cm
=4 cm³/s
Therefore the surface area of the balloon is increased at 4 cm³/s.
Answer :
.
Explanation:
It is given that,
Electric field strength, 
We know that,
Charge of electron, 
Mass of electron, 
From the definition of electric field,
...............(1)
According to Newton's second law, F = ma..........(2)
From equation (1) and (2)




or

So, the horizontal component of acceleration of an electron is
.
Hence, it is the required solution.
Answer:

Explanation:
Given that,
Mass of a boy is 78 kg
Mass of a girl is 65 kg
We need to find the force of gravitational attraction between them if they are 2 m away.
The formula for the gravitational force is given by :

So, the force between them is
.
Human dignity and worth and social justice are TWO OF THE BASIC VALUES OF THE CODE OF ETHICS FOR SOCIAL WORK.
Social workers are those professionals, who promote social change by helping to relieve hardship and suffering. Social work is committed to five basic values, which are:
1. Human dignity and worth
2. Social justice
3. Service to humanity
4. Integrity
5. Competence.
The human dignity and self worth value holds that all human beings have intrinsic value, right to well being, right to self fulfillment and control over their own lives.
The social justice value states that there should be fair and equitable distribution of resources to meet basic human needs and all citizens should have access to public resources in order to achieve full potential.