Answer:
The displacement of the volleyball is 2.62 m
Explanation:
Given;
initial velocity of the volleyball, u = 7.5 m/s
final velocity of the volleyball, v = 2.2 m/s
displacement of the volleyball, d = ?
Apply the following kinematic equation;
v² = u² - 2gd
2gd = u² - v²

Therefore, the displacement of the volleyball is 2.62 m
The stone's altitude at time
is given by

where
is the acceleration due to gravity. The stone reaches the ground when
:

Answer:
Force is 57.69 N to the opposite direction of motion of dolphin.
Explanation:
We have force is the product of mass and acceleration.
That is
Force = Mass x Acceleration
F = ma
Mass of dolphin, m = 30 kg
We have equation of motion, v = u + at
Final velocity, v = 7 m/s
Initial velocity, u = 12 m/s
Time, t = 2.60 s
Substituting
7 = 12 + a x 2.6
a = -1.92 m/s²
Force, F = 30 x -1.92 = -57.69 N
So the force is 57.69 N to the opposite direction of motion of dolphin.