A particle is projected in air at some angle to the horizontal, moves along parabola as shown in figure where x and y indicate horizontal and vertical directions, respectively . Shown in the diagram, direction of velocity and acceleration at points A, B and C.

Explanation

Let the projectile be projected with velocity u at an angle `theta ` with the horizontal .
At point A `v_("XA)=u cos thea `
`v_("YA")=u sin theta -"gt"_(1)`
`therefore v_(A)=sqrt(v_("XA")^(2)+v_("YA")^(2))`
`rArr a_(A)=-g`
At point B `v_("XB")=u cos theta, v_("YB")=0`
`therefore v_(B)=sqrt(v_("XB")^(2)+v_("YB")^(2))`
`rArr a_(B)=-g`
At point C `v_(XC)=u cos theta , v_("YC")= u sin theta -"gt"_(2)`
`v_(c)=sqrt(v_("XC")^(2)+v_("YC")^(2))`
`rArr a_(c)=-g`