Sedimentary rocks are turned into metamorphic rocks by heat and pressure
<u>Answer:</u>
By 1700, 13 elements had been discovered and isolated by the Scientists.
Option (a)
<u>Explanation:</u>
- The copper, gold and silver are the elements which have been known from thousands of years. In the early days of 1700, the scientist discovered only 12 elements, later on one more element was discovered.
- Later in the era of 1800, the scientist research and find new elements, where they organize it methodically, according to the physical and chemical properties.
- After a long research in 1900 scientist discovered more than 80 elements.
The force of gravity is the force with which massively large objects such as the earth attracts another object towards itself. All objects of the earth exert a gravity that is directed towards the center of the earth. Therefore, the force of gravity of the earth is equal to the mass of the object times acceleration due to gravity.
<span>F = ma </span>
<span>4.9N = m (9.8 m/s^2), note that N (newtons) = kg-m/s^2 </span>
m = 0.5 kg
<span>The mass of the object is 0.5kg.</span>