B. it was necessary to see data from more plants before the conclusion could be accepted.
The Earth itself is a source of terrestrial radiation. Radioactive materials including uranium, thorium, and radium exist naturally in soil and rock. Essentially all air contains radon<span> , which is responsible for most of the dose that Americans receive each year from natural background sources.</span>
<span>Force = Work done / distance = 4Nm / 2m = 2N</span>
I think it was either Robert Hook or Anton Van Leevwen Hoek
