Mechanical advantage is the amount by which a machine multiplies input force. It is a measure of the force amplification using a tool or machine system.
The average speed of the bus from Lansing to Detroit is

while the average speed of the bus from Detroit to Lansing is

The distance covered by the bus in the two trips is the same (the distance between the two cities), therefore, the average speed of the round trip can be calculated as the mean of the two speeds:
If the runner is running in a circular track then yes when something or someone is moving in a circular motion at a constant speed they are indeed accelerating. They’re accelerating because the direction of the velocity vector is changing
That would be the second law
Explanation:
The net force of each square is the combination of the forces in each direction. The direction is the... direction the square would go in due to the net force. The magnitude of the net force is how large it is. So if you had a force pushing 2N to the left and 1N to the right, then the net force would be 1N to the left; because the two oppose eachother. If they were going in the same direction, then they'd add to each other. And perpendicular net forces (like one pushing up and another pushing left) can create net forces in diagonal directions.
I'm not going to do all of these for you because they're basically all the same thing and it's good practice for you anyway. But I'll do the first three just so you can get the idea:
1. The net force's magnitude is 4N and it's direction is to the right.
2. The net force's magnitude is 4N and it's direction is to the left.
3. The net force's magnitude is 0N and it has no direction because they are equal forces acting in opposite directions.