Seat belts and air bags save lives by reducing the forces exerted on the driver and passengers in an automobile collision. cars are designed with a "crumple zone" in the front of the car. in the event of an impact, the passenger compartment decelerates with the car. by contrast, an unrestrained occupant keeps moving forward with no loss of speed (newton's first law! ) until hitting the dashboard or windshield, as we saw in figure 4.2. these are unyielding surfaces, and the unfortunate occupant then decelerates over a distance of only about 5 mm.
a. a 60 kg person is in a head-on collision. the car's speed at impact is 15 m/s.
estimate the net force on the person if he or she is wearing a seat belt and if the air
bag deploys.
b. estimate the net force that ultimately stops the person if he or she is not restrained
by a seat belt or air bag.
c. how does these two forces compare to the person's weight

nec chapter 5 contains

c. information on special occupancy areas

nec chapter 6 covers

a. special equipment

which of the following rules contain the words shall or shall not and must be adhered to?

b. mandatory rules

which of the following rules identify actions that are allowed but not required and typically cover options or alternative methods?

c. optional rules

which of the following serves as the introduction to the nec and provides an overview of the book?

a. nec article 90

organizations that test products for safety are

c. nrtls

the nec is published by the

a national fire protection association

the nec is divided into

b. 9 chapters

the nec provides informative annexes for

c. informational materials and examples

two terms from nec article 100 that trainees should become familiar with are

b. labeled and listed

explanation:

so here is the information for current research:

-nrel's geothermal analysts, scientists, and engineers perform a full range of research from developing advanced methods of locating and accessing geothermal resources to exploring innovative technologies to extract and produce clean energy from the heat of the earth

and here is the information for the technology of geothermal energy:

-it's clean and sustainable

-resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma

-almost everywhere, the shallow ground or upper 10 feet of the earth's surface maintains a nearly constant temperature between 50° and 60°f (10° and 16°c)

-geothermal heat pumps can tap into this resource to heat and cool buildings

-a geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building

-in the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system

-in the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger

-the heat removed from the indoor air during the summer can also be used to provide a free source of hot water