9 is D I believe, I don't know about 10
the speed of the ball before it reaches the pool of water would be 9.91 m/s.
Question 1) excited and moving around a lot.
Question 2) heat
Question 3) specific heat
Question 4) As temperature increases, energy transferred increases.
Hope these answers help!
(a) Let
be the maximum linear speed with which the ball can move in a circle without breaking the cord. Its centripetal/radial acceleration has magnitude

where
is the radius of the circle.
The tension in the cord is what makes the ball move in its plane. By Newton's second law, the maximum net force on it is

so that

Solve for
:

(b) The net force equation in part (a) leads us to the relation

so that
is directly proportional to the square root of
. As the radius
increases, the maximum linear speed
will also increase, so the cord is less likely to break if we keep up the same speed.