The independent variable is how much weight you add to the boat.
The dependent variable is: Did it or did it not sink yet ?
Answer: b or c
Explanation: on khan academy
Answer:

Explanation:
The elastic potential energy of a spring is given by
, where
is the spring constant of the spring and
is displacement from point of equilibrium.
When released, this potential energy will be converted into kinetic energy. Kinetic energy is given by
, where
is the mass of the object and
is the object's velocity.
Thus, we have:

Substituting given values, we get:

Answer:
the vertical acceleration of the case is 1.46 m/s
Explanation:
Given;
mass of the clarinet case, m = 3.07 kg
upward force applied by the man, F = 25.60 N
Apply Newton's second law of motion;
the upward force on the clarinet case = its weight acting downwards + downward force due to its downward accelaration
F = mg + m(-a)
the acceleration is negative due to downward motion from the top of the piano.
F = mg - ma
ma = mg - F

Therefore, the vertical acceleration of the case is 1.46 m/s²