Answer:
c)the gravitational forces of people is so small it is overshadowed by that of earth.
Explanation:
The gravitational force between two objects is given by:

where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is the distance between the two objects
From the formula, we see that the gravitational force depends on the masses of the objects: since the mass of the Earth (
is much much larger than the average mass of one person (80-100 kg), then the gravitational force exerted by the Earth on a person is also much much larger than the gravitational force between two people.
Number 2- Liquids
Number 3- Cells
Answer:
B, the car travels around a circular track at 30 m.
Explanation:
Answer:
- 0.09 % of the original radioactive nucllde its left after 10 half-lives
- It will take 241,100 years for 10 half-lives of plutonium-239 to pass.
Explanation:
The equation for radioactive decay its:
,
where N(t) its quantity of material at time t,
its the initial quantity of material and
its the mean lifetime of the radioactive element.
The half-life
its the time at which the quantity of material its the half of the initial value, so, we can find:

so:




So, after 10 half-lives, we got:




So, we got that a 0.09 % of the original radioactive nucllde its left.
Putonioum-239 has a half-life of 24,110 years. So, 10 half-life will take to pass

It will take 241,100 years for 10 half-lives of plutonium-239 to pass.