Answer:
At a stream's headwaters, often high in the mountains, gradients are steep. The stream moves fast and does lots of work eroding the stream bed.As a stream moves into lower areas, the gradient is not as steep. Now the stream does more work eroding the edges of its banks.
hope that helps bby<3
Percent composition by mass of oxygen =
((16.0*6)/(40.1+2*(14.0+16.0*3)))*100%
= 58.5%
therefore, the answer is D
Answer:The first task of a nuclear weapon design is to rapidly assemble a supercritical mass of fissile uranium or plutonium. A supercritical mass is one in which the percentage of fission-produced neutrons captured by another fissile nucleus is large enough that each fission event, on average, causes more than one additional fission event. Once the critical mass is assembled, at maximum density, a burst of neutrons is supplied to start as many chain reactions as possible. Early weapons used a modulated neutron generator codenamed "Urchin" inside the pit containing polonium-210 and beryllium separated by a thin barrier. Implosion of the pit crushed the neutron generator, mixing the two metals, thereby allowing alpha particles from the polonium to interact with beryllium to produce free neutrons. In modern weapons, the neutron generator is a high-voltage vacuum tube containing a particle accelerator which bombards a deuterium/tritium-metal hydride target with deuterium and tritium ions. The resulting small-scale fusion produces neutrons at a protected location outside the physics package, from which they penetrate the pit. This method allows better control of the timing of chain reaction initiation.
Explanation:
dog!
this is because the first energy comes from plants bc they can make their own food— therefore, energy :)
