Results
Q1. If the cross-sectional area of an airflow is mechanically reduced:
Ans: – the mass flow remains constant and the velocity of the airflow increases.
Q2. The statement, Pressure plus Kinetic energy equals constant, refers to:
Ans: – Bernoulli’s theorem.
Q3. If the velocity of an air mass is increased:
Ans: – the kinetic energy will increase, the dynamic pressure will increase and the static pressure will decrease.
Q4. When considering a streamlined airflow, which of the following statements is correct? 1. A resultant decrease in static pressure is indicated by streamlines shown close together. 2. An increase in velocity is indicated by streamlines shown close together. 3. Accelerating airflow with a resultant decreasing static pressure is indicated by converging streamlines. 4. Diverging streamlines indicate decelerating airflow with a resultant increasing static pressure.
Ans: – 1, 2, 3 and 4.
Q5. If the pressure on one side of a surface is lower than on the other side:
Ans: – a force per unit area will exist, acting in the direction of the lower pressure.
Q6. When considering a streamtube, which of the following statements is correct? 1. Different sizes of stream tube are manufactured to match the wingspan of the aircraft to which they will be fitted. 2. A streamtube is a concept to aid understanding of aerodynamic force generation. 3. There is no flow into or out of the streamtube through the “walls”, only flow along the tube. 4. A streamtube is an imaginary tube made up of streamlines.
Ans: – 2, 3 and 4.
Q7. In accordance with the principle of continuity: 1. air accelerates when the cross-sectional area of a streamline flow is reduced. 2. when air accelerates the density of air in a streamline flow is increased. 3. air decelerates when the cross-sectional area of a streamline flow is increased. 4. changes in cross-sectional area of a streamline flow will affect the air velocity. Which of the preceding statements are true?
Ans: – 1, 3 and 4.
Q8. In accordance with Bernoulli’s theorem: 1. if a streamline flow of air decelerates, its kinetic energy will decrease and the static pressure will increase. 2. if a streamline flow of air accelerates, its kinetic energy will increase and the static pressure will decrease. 3. if a streamline flow of air is accelerated, the dynamic pressure will increase and the static pressure will increase. 4. if a streamline flow of air is decelerated, its dynamic pressure will decrease and the static pressure will increase. The combination of correct statements is:
Ans: – 1, 2 and 4.
Q9. The statement, “Energy and mass can neither be created nor destroyed, only changed from one form to another”, refers to:
Ans: – the principle of continuity.
