A baseball is thrown through the air. It's initial velocity, described as a vector, is → v ( t = 0 ) = 17.1 ˆ i + 14.7 ˆ j m / s The ball accelerates only due to gravity. You can take the magnitude of this acceleration to be 9.8 m / s 2 . What is the acceleration of the ball, described as a vector?

 a = - 9.8 j ^   m/s²

Explanation:

This is a projectile launch problem, they give us the initial velocity in the two components

         v₀ₓ = 17.1 m / s

          = 14.7 m / s

They indicate that the only acceleration that exists is the acceleration of gravity, which acts in the direction towards the center of the Earth, in general in a coordinate system it coincides with the direction of the y axis.

           a = - g j ^

           a = - 9.8 j ^  m /s²

d) the number of neutrons plus the number of protons

i guess it’s a and b