A rescue helicopter is hovering over a person whose boat has sunk. One of the rescuers throws a life preserver straight down to the victim with an initial velocity of 1.40 m/s and observes that it takes 1.8 s to reach the water. (a) List the knowns in this problem. (b) How high above the water was the preserver released? Note that the downdraft of the helicopter reduces the effects of air resistance on the falling life preserver, so that an acceleration equal to that of gravity is reasonable.
Astronomy 103: Chapter 1 Chapter 1: Discovering the Night Sky Part One Guiding Questions 1. What methods do scientists use to expand our understanding of the universe 2. What makes up our solar system 3. What are stars Do they last forever 4. What are galaxies What do astronomers learn by studying them 5. How does measuring angles help astronomers learn about objects in the sky 6. What is powers-of-ten notation, and why is it useful in astronomy 7. Why do astronomers measure distances in astronomical units, light- years, and parsecs 8. How does studying the cosmos help us on earth Scientific method (The Process of Doing Science) A reiterative process based on observations, logic, and skepticism Hypothesis A concept or idea that seems to explain a phenomenon or set of observations Model A set of hypothesis that have withstood observational or experimental tests Theory A set of related hypotheses can be pieced together into a self- consistent description to natural observations Law of Physics Theories that accurately describe the workings of physical reality, and have stood the test of time and been shown to have great and general validity -The star we call the sun and all the celestial bodies that orbit the sun Including earth The other seven planets (mercury, Venus, mars, Jupiter, Saturn, Uranus, and Neptune) All their various moons Smaller bodies such as asteroids and comets By studying stars and nebulae, astronomers d