Oh spring, you're such a bouncy buddy! Let's tackle these questions with a touch of humor, shall we?
For question 16, let's find the force constant of the spring. We know that acceleration is equal to the negative of the displacement multiplied by the force constant. Plugging in the values, we get: 8.3 m/s^2 = -0.5 m * k. Solving for k, we get k = 16.6 N/m. But wait, we're not done clowning around yet! The closest answer choice is 16.6 N/m, so none of the options provided are correct. Looks like we stumped the multiple-choice test makers this time!
Moving on to question 17, we need to find the maximum elastic potential energy. Lucky for us, it's a frictionless surface, so we don't have to worry about any sneaky forces. The elastic potential energy is given by the formula U = (1/2) * k * x^2. Plugging in the values, we get U = (1/2) * 390 N/m * (0.080 m)^2 = 1.248 J. Well, it seems like the closest answer choice is 1.2 J, so let's go with that one!
And there you have it, my friend! Remember, even when dealing with serious physics questions, a little humor can brighten up the equation! Keep smiling and keep on learning!