Take the object's starting direction of motion to be the positive direction, so that a stopping force acts in the opposite direction. By Newton's second law, the object undergoes an acceleration <em>a</em> such that
-15 N = (20 kg) <em>a</em>
Solve for <em>a</em> :
<em>a</em> = - (15 N) / (20 kg) = -0.75 m/s²
The object's velocity <em>v</em> at time <em>t</em> is then given by
<em>v</em> = 3 m/s + (-0.75 m/s²) <em>t</em>
so the time it takes for the object to slow to a rest is
0 = 3 m/s + (-0.75 m/s²) <em>t</em>
<em>t</em> = (3 m/s) / (0.75 m/s²) = 4.0 s
Archaeologists use radioactive decay of an isotope of the element <u>carbon.</u> Because it has a fairly short half-life, and is found in anything that was once living.
<h3>What is radioactivity?</h3>
The act of producing radiation spontaneously is known as radioactivity. This is accomplished by an unstable atomic nucleus that want to give up some energy in order to move to a more stable form.
Archaeologists use radioactive decay of an isotope of the element <u>carbon.</u> Because it has a fairly short half-life, and is found in anything that was once living.
Hence, <u>carbon</u> is used the correct answer for the blank.
To learn more about the radioactivity, refer to the link;
brainly.com/question/1770619
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Cell theory states that all living things are made of cells. And cells can only come from other cells, this disproves spontaneous generation and therefore proves the view that organisms can grow from food or dirt is wrong.
32f. That's because the force is directly proportional to the product of the masses and inversely proportional to the square of the distance. So you get 2•(1/1/4)^2=2•16=32
