c. acceleration is vertical, while the velocity can be in any direction. d. acceleration is vertical and the velocity is horizontal. B. True or False. Write T if the statement is true, and F if it is false. 7. The horizontal velocity of a projectile is constant. 8. Projectiles travel with a parabolic trajectory due to the influence of gravity. 9. The horizontal motion of a projectile is dependent of its vertical motion. 10. There are no horizontal forces acting upon projectiles and thus no horizontal acceleration. 11. A velocity is any object thrown horizontally or vertically upon which the only force acting is gravity.