A. Acceleration is the answer to you question. When an object changes velocity it can accelerate.<span />
To calculate the average acceleration of the ball we use the formula,

Here,
is the final velocity of the ball and
is the initial velocity of the ball t is the time in contact with the wall.
Given
towards the wall and 
away from the wall and
.
Substituting these values in above formula , we get

Here
is negative because ball is moving away from the wall.

Therefore, average acceleration of the ball is
(away from the wall).
Answer:
magnetic force
Explanation:
when some one gets charged up by maybe static eletricity the person will sustain the energy and the energy will make a force field around the person which can and will attract paper and he will be attractive
Answer:
B) Electrons and protons
Explanation:
Each proton has a positive charge, and each electron has a negative charge. If the atom is electrically neutral, there must be the same number of electrons and protons.
A) and C) are wrong. Neutrons have no charge, so they can't counteract that of the protons or the electrons.
D) is wrong. The atomic number is the number of protons, and the mass number is the number of protons plus neutrons. The neutrons can't counteract the charge of the protons,
Setting up an integral of
rotation is used as a method of of calculating the volume of a 3D object formed
by a rotated area of a 2D space. Finding the volume is similar to finding the
area, but there is one additional component of rotating the area around a line
of symmetry.
<span>First the solid of revolution
should be defined. The general function
is y=f(x), on an interval [a,b].</span>
Then the curve is rotated
about a given axis to get the surface of the solid of revolution. That is the
integral of the function.
<span>It all depends of the
function f(x), which must be known in order to calculate the integral.</span>