If we continued this format, we would call displacement s s with components s x s x and s y s y. (Note that in the last section we used the notation A A to represent a vector with components A x A x and A y A y. The magnitudes of these vectors are s, x, and y. Figure 3.34 illustrates the notation for displacement, where s s is defined to be the total displacement and x x and y y are its components along the horizontal and vertical axes, respectively. (This choice of axes is the most sensible, because acceleration due to gravity is vertical-thus, there will be no acceleration along the horizontal axis when air resistance is negligible.) As is customary, we call the horizontal axis the x-axis and the vertical axis the y-axis. The key to analyzing two-dimensional projectile motion is to break it into two motions, one along the horizontal axis and the other along the vertical. This fact was discussed in Kinematics in Two Dimensions: An Introduction, where vertical and horizontal motions were seen to be independent. The most important fact to remember here is that motions along perpendicular axes are independent and thus can be analyzed separately. In this section, we consider two-dimensional projectile motion, such as that of a football or other object for which air resistance is negligible. The motion of falling objects, as covered in Problem-Solving Basics for One-Dimensional Kinematics, is a simple one-dimensional type of projectile motion in which there is no horizontal movement. The object is called a projectile, and its path is called its trajectory. Projectile motion is the motion of an object thrown or projected into the air, subject to only the acceleration of gravity.

Apply the principle of independence of motion to solve projectile motion problems.

Determine the location and velocity of a projectile at different points in its trajectory.

Identify and explain the properties of a projectile, such as acceleration due to gravity, range, maximum height, and trajectory.

Imagine if you had to rederive the Pythagorean theorem every time you wanted to use it instead of just being able to plug the numbers into the formula.By the end of this section, you will be able to: Also, once you have a general expression for a thing, you've essentially solved that class of problem. In general, whenever you can – that is, whenever it's not prohibitively difficult – you should try to solve the thing symbolically to gain the greatest insight. For example, Maybe the expression for the area of a circle shows up somewhere in the final expression, which can suggest a different derivation or interpretation. But when you solve the thing symbolically, you can interpret the equation, see clearly what's proportional to what, any algebraic symmetry (functional symmetry, being able to swap variables, so on), you can see patterns or that some other quantity might be hidden in the thing. When you solve a thing numerically, you just get some number (or a vector, etc.) at the end (and maybe some units).

Yeah, and it's actually a great way to gain insight into the nature of the thing.

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Projectile motion physics