If element X consists of 64.6% of atoms with a mass of 34.0 u, 18.2% of atoms with a mass of 35.0 u, and 17.2% of atoms with a mass of 36.0 u, what is the average atomic mass of element X to the nearest hundredth?

The mass of 60.4% of the atoms of an element is 68.9257 u. There is only one other natural isotope of that element, and its atomic mass is 70.9249 u. Calculate the average atomic mass of the element. Using the periodic table and/or the table of the elements, write its symbol and name.

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j