This question is from dynamics can you please explain in det

This question is from dynamics, can you please explain in detail. I can\'t find this in the book.

Which of the following is always zero?

Solution

Tangential component of acceleration is always zero .They are talking about projectile motion.In projectile motion normal component of acceleration is acceleration due to gravity but there is no tangential component.Also velocity has both tangential and normal components.Thus, only tangential component of acceleration is zero.