The speed that matters
The actual speed of a subject is less important than how fast it travels across the frame, which sounds obvious, but it’s easy to be over-impressed by the moving thing, such as a racing car, motorcycle or low-flying jet. If something takes a second to cross the frame, you’ll need a shutter speed of at least 1/500 sec to freeze its movement.
From the same camera position, a moving subject travels more slowly through the frame with a wide-angle lens than with a long telephoto, which magnifies movement as well as other things.
A smoothly travelling subject, such as a vehicle on a road, moves fastest through the frame when it’s moving at right angles to you and the camera, much less when it’s coming diagonally toward you, and hardly at all when coming straight at you (that doesn’t remove focus issues, though!)
Parts of subjects can move much faster than you might expect inside the frame – for instance, a hand gesture from someone talking, or the blink of an eyelid, can be extremely quick.
Panning slows down the in-frame movement of a smoothly travelling subject, but not its moving parts (such as the spokes of a passing moped below). The main movement of the moped is easily frozen by panning at 1/250 sec, but the rapidly revolving wheel spokes inevitably blur