1) Pushing on a car will not always change the car's mechanical energy, but it does change yours since your physically using most of your energy to push the car.
2) In order for a cars kinetic energy to increase, the car has to be in motion when it is going down a hill, because when you go down hills and objects like that; you tend to increase in kinetic energy.
4 n to the right is the net force
Answer: The body will be in a position of rest
Explanation:
Since both forces are equal and acting in opposite direction on the body. It will make the body to be in a state of rest or equilibrium because the sum of the forces acting in the body will be zero.
The average speed of the whole travel is equal to <u>400 mph</u>.
Why?
From the statement, we know that whole travel is divided into three parts. For the first part (traveling from New York to Chicago), we have that it was 3.25 hours and the covered distance was half of the total distance (1400mi). For the second part, we have that it was 1 hour (layover time), and the covered no distance. For the third part (traveling from Chicago to Los Angeles), we have that it was 2.75 hours, and it took the other half of the total distance (1400mi).
We can calculate the average speed of the whol travel using the following formula:

Now, substituting and calculating, we have:


Hence, we have the average speed of the whole travel is equal to 400 mph.
Have a nice day!