Homework

How does Newton’s third law of motion explain the properties of a rocket’s propulsion system in outer space?Newton’s third law states that for every action, there is an equal and opposite reaction. In a rocket’s propulsion system, the expulsion of gas out of the rocket’s engine creates a force in the opposite direction, propelling the rocket forward. This principle operates effectively in the vacuum of outer space, where there is no atmospheric resistance.

How does the autonomic nervous system regulate heart rate and blood pressure in the human body?The autonomic nervous system (ANS) regulates heart rate and blood pressure through its two branches: the sympathetic and parasympathetic nervous systems. The sympathetic nervous system increases heart rate and blood pressure by releasing norepinephrine, which stimulates the heart and constricts blood vessels. Conversely, the parasympathetic nervous system decreases heart rate and blood pressure by releasing acetylcholine, which slows the heart and dilates blood vessels. These systems work together to maintain homeostasis and respond to stress or relaxation.

What are the main layers of the Earth and their characteristics?The Earth is composed of four main layers: the crust, mantle, outer core, and inner core. The crust is the outermost layer, solid and thin. The mantle beneath is semi-solid and convective. The outer core is liquid iron and nickel, while the inner core is solid iron and nickel, extremely hot and dense.

How do scientists determine the age of the universe using cosmic microwave background radiation and the expansion rate of the universe?Scientists determine the age of the universe by analyzing the cosmic microwave background (CMB) radiation, which provides a snapshot of the early universe. By measuring the expansion rate of the universe, known as the Hubble constant, and combining it with data from the CMB, scientists can calculate the time elapsed since the Big Bang, estimating the universe’s age to be approximately 13.8 billion years.