Answer:
V = 6 m/s
Explanation:
Given that,
Initial speed of an object is 20 m/s
Final speed of an object is 10 m/s
Time, t = 5 s
We need to find the average speed of the object during these 5 seconds. Let it is equal to V. Here, time is same. The average speed is given by :

So, the average speed of the object is 6 m/s.
I don’t know what book you’re talking about so I can’t help but have a look online, you may be able to find it if you search up the book name and look around a few websites
Answer:
Final volumen first process 
Final Pressure second process 
Explanation:
Using the Ideal Gases Law yoy have for pressure:

where:
P is the pressure, in Pa
n is the nuber of moles of gas
R is the universal gas constant: 8,314 J/mol K
T is the temperature in Kelvin
V is the volumen in cubic meters
Given that the amount of material is constant in the process:

In an isobaric process the pressure is constant so:



Replacing : 

Replacing on the ideal gases formula the pressure at this piont is:

For Temperature the ideal gases formula is:

For the second process you have that
So:



