30 points
part one:
a crate is pulled by a force (parallel to the
incline) up a rough incline. the crate has an
initial speed shown in the figure below. the
crate is pulled a distance of 5.59 m on the
incline by a 150 n force.
the acceleration of gravity is 9.8 m/s^2
a) what is the change in kinetic energy of
the crate?
answer in units of j.

part two:
b.)what is the speed of the crate after it is
pulled the 5.59 m?
answer in units of m/s.

series resistors just add.

rt = r1 + r2 + r3

rt = 5 + 3 + 8

rt = 16 ohms

geologists use radiometric dating to estimate how long ago rocks formed, and to infer the ages of fossils contained within those rocks. the methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. so, they do this by giving off radiation. this process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay. the thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life. so, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance.

the answer is c. the mass of the platinum sample is greater than the mass of the lead sample. as i explained in a previous answer, if they are the same volume, but one is heavier, then it must be more dense. in this particular example, the platinum is more dense than the lead, and therefore has more mass.