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# 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 parabola.

If we break this motion into x- and y-components, the motion becomes easy to understand. 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.

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