At the ground the ball will always have velocity along the direction of gravity. If upward motion is taken positive it will always have negative velocity at the ground because, if the ball was given an initial upward velocity then gravity will decelerate it and bring it down with a negative final velocity. If the ball is given an initial downward velocity then the ball will be further accelerated by gravity in the downward direction only, again maintaining negative direction. The magnitude however in both cases will be different. the final velocity at the ground will have higher magnitude in case of elevator moving downwards.
Answer:
1. the electric potential energy of the electron when it is at the midpoint is - 2.9 x 
J
2. the electric potential energy of the electron when it is 10.0 cm from the 3.00 nC charge is - 5.04 x J
Explanation:
given information:
= 3 nC = 3 x 
C
= 2 nC = 2 x C
r = 50 cm = 0.5 m
the electric potential energy of the electron when it is at the midpoint
potential energy of the charge, F
F = k 
where
k = constant (8.99 x 
)
electron charge, 
= - 1.6 x 
C
since it is measured at the midpoint,
r = 
= 0.25 m
thus,
F = 
= k
+ k
= 
(
)
= (8.99 x 
)( - 1.6 x )(3 x +2 x )/0.25
= - 2.9 x J
the electric potential energy of the electron when it is 10.0 cm from the 3.00 nC charge
= 10 cm = 0.1 m
= 0.5 - 0.1 = 0.4 m
F = k + k
= 
(
+
)
= (8.99 x )( - 1.6 x )(3 x /0.1+2 x /0.4)
= - 5.04 x J
<span>Science is always defined as the body of knowledge and linked to something
related to the physical world, phenomena and lives of everything that exist on
Earth. Science is categorized in various ways. Pure, practical or theoretical, is the largest
distinction of science or whether
science is applied. Generally, pure
science is subdivided into Physical sciences, Earth sciences, and Life
sciences. Physical sciences deal with
energy and matter, Earth sciences explain Earth’s phenomena, to the solar
system where it belongs and its atmosphere. And finally, life sciences describe
internal processes of living organisms, its relationship to each other and to
its environment.</span>
S=125km
t=2h
v=s/t=125/2=62,5km/h
or 62,5/3,6=17,36m/s
