a. 7.0 m/s
First of all, we need to convert the angular speed (1200 rpm) from rpm to rad/s:

Now we know that the row is located 5.6 cm from the centre of the disc:
r = 5.6 cm = 0.056 m
So we can find the tangential speed of the row as the product between the angular speed and the distance of the row from the centre of the circle:

b. 
The acceleration of the row of data (centripetal acceleration) is given by

where we have
v = 7.0 m/s is the tangential speed
r = 0.056 m is the distance of the row from the centre of the trajectory
Substituting numbers into the formula, we find

Answer:
The speed of the water shoot out of the hole is 20 m/s.
(d) is correct option.
Explanation:
Given that,
Height = 20 m
We need to calculate the velocity
Using formula Bernoulli equation

Where,
v₁= initial velocity
v₂=final velocity
h₁=total height
h₂=height of the hole from the base
Put the value into the formula




Hence, The speed of the water shoot out of the hole is 20 m/s.
The loss or conservation of kinetic energy is the difference between an elastic and an inelastic collision. Kinetic energy is not preserved in an inelastic collision, and it will change forms into sound, heat, radiation, or another form. The kinetic energy in an elastic collision is preserved and does not change forms.
F = ma
6.25 N = 0.4 kg · a
a = (6.25/0.4) m/s² since N=kg·m/s²
a = 15.625 m/s²
The answer is c) 15.6 m/s²
(Note that the mass of the soccer player is irrelevant.)