When skaters want to launch themselves down the half-pipe, how do they make sure they'll have enough energy to stick their landing? Likewise, when engineers are designing a skate park, how do they know how steep to make the ramps? In both cases, they must consider the total energy needed to achieve a successful run. This makes a skate park an excellent place to explore the law of conservation of energy while applying the engineering design process.

d.) continue to rise rapidly

the earth’s crust is broken into separate pieces called tectonic plates (fig. 7.14). recall that the crust is the solid, rocky, outer shell of the planet. it is composed of two distinctly different types of material: the less-dense continental crust and the more-dense oceanic crust. both types of crust rest atop solid, upper mantle material. the upper mantle, in turn, floats on a denser layer of lower mantle that is much like thick molten tar.

each tectonic plate is free-floating and can move independently. earthquakes and volcanoes are the direct result of the movement of tectonic plates at fault lines. the term fault is used to describe the boundary between tectonic plates. most of the earthquakes and volcanoes around the pacific ocean basin—a pattern known as the “ring of fire”—are due to the movement of tectonic plates in this region. other observable results of short-term plate movement include the gradual widening of the great rift lakes in eastern africa and the rising of the himalayan mountain range. the motion of plates can be described in four general patterns:

collision: when two continental plates are shoved together

subduction: when one plate plunges beneath another (fig. 7.15)

spreading: when two plates are pushed apart (fig. 7.15)

transform faulting: when two plates slide past each other (fig. 7.15)

the use of electrical signals that transit messages is know as

the values of the selma marchers was to bring   their ability to vote into law. mlk was not hat march, which was protesting toward lbj