Answer:
A. 98,000 J
Explanation:
The gravitational potential energy of an object is given by
U = mgh
where
m is the mass of the object
g is the gravitational acceleration
h is the heigth above the ground
In this problem,
m = 2000 kg
g = 9.8 m/s^2
h = 5.0 m
Substituting into the equation, we find
The reaction time of Boris is t(r), so before that, Boris will not have jumped. Thus, H(b)(t) = 0
The vertical displacement will simply be
D(t) = H(a)(t)
At the time that I'll call ' Q ', the height of the stone that was
dropped from the tower is
H = 50 - (1/2 G Q²) ,
and the height of the stone that was tossed straight up
from the ground is
H = 20Q - (1/2 G Q²) .
The stones meet when them's heights are equal,
so that's the time when
<span>50 - (1/2 G Q²) = 20Q - (1/2 G Q²) .
This is looking like it's going to be easy.
Add </span><span>(1/2 G Q²) to each side.
Then it says
50 = 20Q
Divide each side by 20: 2.5 = Q .
And there we are. The stones pass each other
2.5 seconds
after they are simultaneously launched.
</span>
B.
Both recognized that the elements have repeating properties but Mendeleev realized that there are elements yet to be discovered while Newlands tried to fit the known elements together.
