You use a full 20 liter compressed air tank with a gauge pressure of 220 atm (at the surface) to fill the balloon from zero volume at depth. Given that the product of pressure and volume stays constant in a gas (as long as the temperature stays constant) and that the pressure inside the balloon equals the ambient pressure, what will be the gauge pressure in the tank once the balloon has been filled to the volume required to lift the boat

does anyone know or what?

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.