Answer:
The underlying principle is the bernoulli's principle of fluid flow which states that a slow moving air stream exerts more pressure than a faster moving air stream
Explanation:
The air stream between the car and the truck experiences more drag and therefore has a relatively higher speed than the air stream on the other side of the car, this means the air on the other side exerts more side force on the car, the net side force causes the car to swoop sideways towards the truck.
The same applies to a moving convertible car at high speed. The air outside has a higher relative velocity than the air inside the car. The inside air exerts more force on the canvass roof causing it to bulge upwards.
The windows of old train crack due to the pressure from the air within the old train which moves at a lower relative speed to that between the train and the speed train.
The bowling ball is round in shape and red in color.
The bowling ball is smooth and hard.
*The shape of the bowling ball is round.
The color of the bowling ball is red.
The bowling ball is hard.
The bowling ball is smooth.
To solve this problem it is necessary to apply the concepts related to uniaxial deflection for which the training variable is applied, determined as

Where,
P = Tensile Force
L= Length
A = Cross sectional Area
E = Young's modulus
PART A) The elongation of the bar in a length of 200 mm caliber, could be determined through the previous equation, then



Therefore the elongaton of the rod in a 200mm gage length is 
PART B) To know the change in the diameter, we apply the similar ratio of the change in length for which,

Where,
Poission's ratio
= Lateral strain
= Linear strain




Therefore the change in diameter of the rod is 