Answer:
The average velocity is 2 m/s.
Explanation:
The velocity of the particle is the time derivative of its position 
![$v =\frac{dx(t)}{dt} = \frac{d}{dt}[t^2+2] $](https://tex.z-dn.net/?f=%24v%20%3D%5Cfrac%7Bdx%28t%29%7D%7Bdt%7D%20%3D%20%5Cfrac%7Bd%7D%7Bdt%7D%5Bt%5E2%2B2%5D%20%24)
Now the average from 
and 
is
Thus, the average velocity is 2 m/s.
I think it is Letter D, because she already said what to make
The factors that affect vital capacity are :
- Age
- Sex
- Height
- Body mass
- Ethnicity
Explanation:
Vital capacity is the maximum amount of air that a person can exhale once he has filled his lungs with maximum air. So, it is like maximum exhalation after maximum inhalation by a person.
Vital capacity is also equal to Forced Vital Capacity.
Lung usually have their maximum capacity in early adult days and this capacity reduces as the person grows older. So age is the prime factor in this.
A female with same age and height as that of male will have 10-12% less vital capacity than him. So sex is another reason which determines vital capacity.
Person with more height has more vital capacity. This is because lungs capacity is closely related to the third power of person's height.
Person suffering from obesity will have compressed diaphragm, lung and chest cavity , so their vital capacity will be less. So we can say body mass affects vital capacity.
Last factor, ethnicity, is yet to be understood clearly as there is not much evidence of this.
The speed of the car at the bottom of the hill is obtained as, 
According the principle of conservation of energy, the total potential energy of the car will be converted to maximum kinetic energy when the car is at the bottom of the hill.
where;
- <em>v </em><em>is the speed of the car at the bottom of the hill</em>
- <em>h </em><em>is the height of the hill</em>
- <em>g </em><em>is acceleration due to gravity</em>
Thus, the speed of the car at the bottom of the hill is obtained as,
Learn more about conservation mechanical energy here: brainly.com/question/332163
