The kinetic energy of the object just after it starts its motion from the Earth surface is
where m is the object mass and
its initial speed.
When it reaches its maximum height, the object speed is zero and all its kinetic energy converted into gravitational potential energy, which is
where
and h is the maximum height reached by the object.
Since the energy of the object must be conserved, K=U, therefore we can write
and we can solve to find h, the maximum height:
Given: Initial velocity 
Final Velocity 
To find : Height when jumpled 8.0 m/s upwards.
Solution: We already have values of initial velocity and final velocity.
We know, accereration due to gravity is given by 
.
It's negative because when jump it's in opposite direction.
Where h is the height when jumpled 8.0 m/s upwards.
Plugging values of 
64= 225 -19.6h
Subtracting both sides by 225.
64-225= 225 -19.6h-225.
We get,
-161 = -19.6h
Dividing both sides by -19.6, we get
h= 8.2143
Rounding to nearest tenth, we get
h= 8.2 meter.
His height is 8.2 meter when he is jumping 8.0 m/s upwards.
The magnitude of the electrostatic force between the two charges is 
Explanation:
The magnitude of the electrostatic force between two charges is given by Coulomb's law:
where:
is the Coulomb's constant
are the two charges
r is the separation between the two charges
In this problem, we have:
r = 20.0 cm = 0.20 m
Therefore, the force between the charges is
where the negative sign means that the force is attractive, since the two charges have opposite sign.
Learn more about electrostatic force here:
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Answer: B.)by consuming plants
Explanation:
There is about 78% nitrogen is available in the atmosphere. But living beings such as plants does not absorb it directly from the air. Instead they absorb the compounds of nitrogen from the soil. The soil bacteria convert the nitrogen oxides into ammonia, nitrates and nitrites in the soil in this way these bacteria fix atmospheric nitrogen into the soil. The plants absorb these forms of nitrogen, which are essentially required for the synthesis of proteins and nucleic acids. Nitrogen as an element becomes essential ingredients in all biomolecules. We humans and animals eat plants and through them the usable form of nitrogen in the form of biomolecules enters the body.
