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:
not work
Explanation:
in a series circuit, everything meaning the electrons are flowing on one path, therefore, it wouldn continue to work.
Relativistic mean its so fast its a fraction of the sped of light.
Answer:
Explanation:
I suppose it has to do with the way the diagram is drawn. The heat does not reflect which makes both A and B incorrect.
C would have nothing to do with either reflection or refraction.
That only leaves D which is the answer.
Answer:
option b
Explanation:
There is an object pulled inward in an electric field.
We have to find out of the four options given which is true.
a) The object has a neutral charge is false since when electric field pulls the object inward, there is a charge inside.
b) The object has a charge opposite that of the field, this option is correct since there will be an equal and opposite charge created by the object
c) The object has a negative charge will be correct only if the original charge was positive hence wrong
d) The object has a charge the same as that of the field is incorrect since this would be opposite the charge
So only option b is right