Ques: Q: Streamlines are smooth and continuous when flow is laminar, but break up and mix when flow is what? Read this paragraph and choose the correct option from the provided answers: Figure 12.11 shows schematically how laminar and turbulent flow differ. Layers flow without mixing when flow is laminar. When there is turbulence, the layers mix, and there are significant velocities in directions other than the overall direction of flow. The lines that are shown in many illustrations are the paths followed by small volumes of fluids. These are called streamlines. Streamlines are smooth and continuous when flow is laminar, but break up and mix when flow is turbulent. Turbulence has two main causes. First, any obstruction or sharp corner, such as in a faucet, creates turbulence by imparting velocities perpendicular to the flow. Second, high speeds cause turbulence. The drag both between adjacent layers of fluid and between the fluid and its surroundings forms swirls and eddies, if the speed is great enough. We shall concentrate on laminar flow for the remainder of this section, leaving certain aspects of turbulence for later sections. Choices: - atmospheric - volcanic - slow - turbulent A:
Ans: turbulent

Ques: Q: Ionic, covalent, and hydrogen are three important types of what type of interaction between different types of atoms? Read this paragraph and choose the correct option from the provided answers: 2.2 | Chemical Bonds By the end of this section, you will be able to: Explain the relationship between molecules and compounds Distinguish between ions, cations, and anions Identify the key difference between ionic and covalent bonds Distinguish between nonpolar and polar covalent bonds Explain how water molecules link via hydrogen bonds Atoms separated by a great distance cannot link; rather, they must come close enough for the electrons in their valence shells to interact. But do atoms ever actually touch one another? Most physicists would say no, because the negatively charged electrons in their valence shells repel one another. No force within the human bodyor anywhere in the natural worldis strong enough to overcome this electrical repulsion. So when you read about atoms linking together or colliding, bear in mind that the atoms are not merging in a physical sense. Instead, atoms link by forming a chemical bond. A bond is a weak or strong electrical attraction that holds atoms in the same vicinity. The new grouping is typically more stableless likely to react againthan its component atoms were when they were separate. A more or less stable grouping of two or more atoms held together by chemical bonds is called a molecule. The bonded atoms may be of the same element, as in the case of H2, which is called molecular hydrogen or hydrogen gas. When a molecule is made up of two or more atoms of different elements, it is called a chemical compound. Thus, a unit of water, or H2O, is a compound, as is a single molecule of the gas methane, or CH4. Three types of chemical bonds are important in human physiology, because they hold together substances that are used by the body for critical aspects of homeostasis, signaling, and energy production, to name just a few important processes. These are ionic bonds, covalent bonds, and hydrogen bonds. Choices: - forms - conflicts - levels - bonds A:
Ans: bonds

Ques: Q: How does air always flow? Read this paragraph and choose the correct option from the provided answers: Cold air is dense, so it sinks. This creates a center of high pressure. Warm air is less dense so it rises. This creates a center of low pressure. Air always flows from higher to lower pressure. As the air flows, Earth's surface rotates below it causing Coriolis effect. So while the wind blows into the low pressure, it revolves in a circular pattern. This wind pattern forms a cyclone. The same happens while the wind blows out of a high pressure. This forms an anticyclone. Both are shown in Figure below . Choices: - in to out - left to right - low to high - high to low A:
Ans: high to low

Ques: Q: What is the term for a change in an object's motion, which occurs whenever an object is acted upon by an unbalanced force? Read this paragraph and choose the correct option from the provided answers: A change in an object's motionsuch as Xander speeding up on his scooteris called acceleration . Acceleration occurs whenever an object is acted upon by an unbalanced force. The greater the net force acting on the object, the greater its acceleration will be, but the mass of the object also affects its acceleration. The smaller its mass is, the greater its acceleration for a given amount of force. Newton's second law of motion summarizes these relationships. According to this law, the acceleration of an object equals the net force acting on it divided by its mass. This can be represented by the equation:. Choices: - rotation - compression - inclination - acceleration A:
Ans:
acceleration