Answer: D) Pulmonary and aortic valves.
Explanation
There are two main heartbeats from a healthy heart.
The first beat is called the S1 or the lub, and it occurs when the atrioventricular valves (comprising the mitral and tricuspid valves) close.
The second beat is called the S2 or the dub, and it occurs when the semilunar valves (comprising the aortic and pulmonary valves) close.
Listening for heart beats is an essential part of cardiac auscultation.
Answer: The noble gases are a group of chemical elements that make up Group 18 on the periodic table. These gases all have similar properties under standard conditions: they are all odorless, colorless, monatomic gases with very low chemical reactivity.
False
their legs were made form the spine of stingrays and they were used to ward of bad storms.
Answer:
It would appear to rise from the horizon to 10° above the horizon. Keep gong north until you reach the North Pole and the pole star will appear directly overhead.
Explanation:
Answer: Because The potential energy you build going up the hill can be released as kinetic energy — the energy of motion that takes you down the hill. Once you start cruising down that first hill, gravity takes over and all the built-up potential energy changes to kinetic energy. Gravity applies a constant downward force on the cars.Potential energy is the energy an object has as a result of its position. Potential energy is stored energy that has not yet been released. Gravitational potential energy is potential energy that results from an object's position in a gravitational field, and is equal to the object's weight multiplied by its height.
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Explanation:
