The AMOUNT of energy the ball has doesn't change. It's 294 joules in Darwin's hand, and it's still 294 joules when the ball hits the ground. It's all PE before he let's it go, and it steadily changes from PE to KE all the way down.
It BEGINS to turn into KE immediately, when Darwin lets go of the ball, and it starts to fall.
More and more PE turns into KE as the ball falls, all the way down.
When the ball hits the ground, it has no more PE left. All of its mechanical energy is then KE.
The speed of a proton after it accelerates from rest through a potential difference of 350 V is
.
Initial velocity of the proton 
Given potential difference 
let's assume that the speed of the proton is
,
Since the proton is accelerating through a potential difference, proton's potential energy will change with time. The potential energy of a particle of charge
when accelerated with a potential difference
is,

Due to Work-Energy Theorem and Conservation of Energy - <em>If there is no non-conservative force acting on a particle then loss in Potential energy P.E must be equal to gain in Kinetic Energy K.E</em> i.e

If the initial and final velocity of the proton is
and
respectively then,
change in Kinetic Energy 
change in Potential Energy 
from conservation of energy,

so, 

To read more about the conservation of energy, please go to brainly.com/question/14668053
<h2>The distance between students is 2.46 m</h2>
Explanation:
The force of attraction due to Newton's gravitation law is
F = 
Here G is the gravitational constant
m₁ is the mass of one student
m₂ is the mass of second student .
and r is the distance between them
Thus r = 
If we substitute the values in the above equation
r = 
= 2.46 m
The gravitational force is inversely proportional to the
square of the distance between their centers. So the
force is greatest when the distance is zero.
Answer:
2. 200N
3.50kg
4.700N
Explanation:
Weight is another word for the force of gravity
Weight is a force that acts at all times on all objects near Earth.
F=m*g
where g=acceleration due to gravity
2. due to the gravitational fields of the earth , assume gravitational acceleration=10m/s2
F=20*10= 200N
3.same as above
mass=Force/gravitational acceleration
mass=500/10 = 50kg
4.force=mass*gravitational acceleration
force=70*10=700N