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A cannon firing at a target

The collision of projectiles

What is the motion of a projectile - can all answers be correct?

Projectile motion is a special case of general two-dimensional motion; the acceleration in the y-direction is the gravitational acceleration and there is no acceleration in the x-direction. The constant acceleration equations must be written for each direction:

The last line assumes that one is taking up and to the right as positive. The -4.9 came from using -9.8 m/s² for the acceleration in the y-direction. x_o and y_o will often be zero, since people usually take the firing point as the origin. However, there are cases where it is convenient to take some other point as the origin, especially if there are two projectiles with different firing points.

When the time to the highest point in the trajectory is to be found (where v_y = 0), this equation is often useful:

The velocity in the x-direction is constant since there is no acceleration in that direction.

Example 1: A Projectile Is Fired

Example 2: A Nasty Golf Course

Example 3: Simultaneous Fireworks

Example 4: A Ball is Thrown From a Roof

Here's a look at a special case in projectile motion.