The zoomed detail is 4000X magnified.
Pressure is getting lower from the left to the right
The small car is in a uniform linear motion
To maintain balance, the heavier child sits nearer to the rotation axis.
It is a type of lever that has the resistance (or output force) in the middle and the effort at one side and the fulcrum on the other side of the resistance
The alcohol burner heats the test tube, and then the test tube heats the cooler water
Wheel and axle of a well