i don't understand the projectile motion...my teacher said...it's a motion of a body confined to a vertical plane, perpendicular to Earth's surface...

I don't get it, can anyone explain to me clearly????
plzzzzz....THX!!!!

If your teacher said that, she was wrong. I doubt if she said exactly that.

Projectile motion is the study of the motion a projectile takes under the influence of gravity. Gravity makes things fall to the earth, including projectiles. However, if a projectile had any amount of horizontal motion, it goes horizontally while falling, making a parabolic path.

See

http://www.glenbrook.k12.il.us/gbssci/phys/Class/vectors/u3l2b.html