Two-Dimensional Motion with Uniform Acceleration
If you’ve got the hang of 1-D motion, you should have no trouble at all with 2-D
motion. The motion of any object moving in two dimensions can be broken into
x- and y-components. Then it’s just a matter of solving two separate
1-D kinematic equations.
The most common problems of this kind on Physics on the test involve projectile
motion: the motion of an object that is shot, thrown, or in some other way
launched into the air. Note that the motion or trajectory of a projectile is a
If we break this motion into x- and y-components, the motion becomes easy to
In the y direction, the ball is thrown upward with an initial velocity
of vy2 and experiences a constant downward acceleration of g = –9.8 m/s2. This is exactly
the kind of motion we examined in the previous section: if we ignore the x-component,
the motion of a projectile is identical to the motion of an object thrown directly up in the air.
In the x direction, the ball is thrown forward with an
initial velocity of vx2 and there is no acceleration acting in the x
direction to change this velocity. We have a very simple situation
where ax = 0 and v0 is constant.