An automobile has just dropped into a river. The car door isapproximately a rectangle, measures 36 in. wide and 40 in. high,and hinges on a vertical side. The water level inside the car is up tothe midheight of the door, and the air inside the car is at atmospheric pressure. Calculate the force required to open the door if the forceis applied 24 in. from the hinge line. See Fig. P2.78. (The driverdid not have the presence of mind to open the window to escape.)
Chapter 1: Chemistry in Our Lives 1.1 What is Chemistry Chemistry is the study of matter and it’s ● Composition ● Structure ● Properties ● Transformation ● Energy conducted when transformation occurs The Birth of Chemistry: Alchemists were one of the first recorded inventors of chemistry and they formed common science practices found in modern medicine today. ● They learned to extract metals ● Designed lab equipment ● Developed lab procedures ● Recognized chemicals have health improving properties ● Evolved medical work and modern chemistry Areas of Chemistry: 1. Organic 2. Physical 3. Biochemistry 4. Analytical 5. Inorganic Why study Chemistry Many fields of work deal with Chemistry, and chemistry can be found all around us when using certain chemicals. A chemical is: a substance that always has the same composition and properties wherever it is found. Examples: Natural chemicals (in plants, animals, and minerals) Synthetic (in drugs, fibers, pesticides, and plastics) Risks/Benefits of Chemistry: Benefits: Improves our lives, used in medicine and building Risks: side effects of medicine, pollution, impact growth 1.2 Scientific Method: Thinking like a Scientist Observation > Hypothesis > Experiments > Conclusion *The hypothesis can be modified if the
