The force required to lift the whale shark is given as 25000 N, and its acceleration is 1.25 m/s^2. We can use Newton's second law of motion, which states that the force (F) applied on an object is equal to the product of its mass (m) and acceleration (a), i.e. F = ma.
Rearranging the equation to solve for the mass, we get:
m = F/a
Substituting the given values, we get:
m = 25000 N / 1.25 m/s^2
m = 20000 kg
Therefore, the mass of the whale shark is approximately 20,000 kg.