i have calc 3 online hw its 4 questions and i need help with it

1)Find the length of the curve given by

where .

2)Given that the acceleration vector is , the initial velocity is , and the initial position vector is , compute:

A. The velocity vector  [removed]  [removed]  [removed] 

B. The position vector  [removed]  [removed]  [removed] 

Note: the coefficients in your answers must be entered in the form of expressions in the variable \emph{t}; e.g. "5 cos(2t)"

3)A gun has a muzzle speed of 50 meters per second. What angle of elevation should be used to hit an object 190 meters away? Neglect air resistance and use  as the acceleration of gravity.

4)If  gives the position of a particle at time , find the time  at which the speed of the particle is minimized.