Why A Low Trajectory Ball Is Not A Slow Spinning Ball

A common misunderstanding in tennis is that a ball that spins faster follows a more vertical path. While true in some cases, it’s not true in all circumstances.

Does This Matter?

Consider that such two dimensional thinking that confuses rotation and revolution is why we once thought the earth was flat, too.

Ball Flight

We impart three primary qualities when we hit a tennis ball:

1) Trajectory of the ball flight,

2) Spin or ball rotation

3) Speed.

These are all relatable but distinct qualities.

Trajectory is the path the ball travels. It can be very steeply arced or it can be less steep and thus flatter. A flatter shaped ball arc does not travel with more speed but it does travel a shorter distance than a steep arced ball therefore it has greater velocity and will reach its target sooner.

When we talk about a non-rotation ball we should remember that there is no such thing as a non-rotating ball struck in tennis. If a ball travels any distance, it spins. If you can throw a ball 60 feet and make it rotate just five times, drop your tennis racket and sign your multi-million dollar contract with the Yankees as their new knuckle-ball ace. Spin is a matter of magnitude and direction.

Diagonal Spin

The common and unfortunate misconception is that the ball only spins on the vertical axis and therefore there are only two kinds of spin: topspin or forward spin, and slice or backspin. The ball however can and most often does spin on a horizontal axis or tilted axis. This horizontal spin results in the ball moving horizontally when it lands, and this effect has been called “The Fade and “The Draw”, by coach and author Chuck Tomlin, using a familiar term from golf. It’s important to understand that when a ball is moving with greater diagonal spin it will likely have less arc and thus be “flatter” but it can still have more spin than a highly arced traditional topspin shot.

The Fact Of Physics

The greater the ball velocity, the greater the rotation frequency the ball will have. So a ball rotating with a forward vector will slow very little and actually accelerate after bouncing from its impact force restitution.

A common way to describe a shot hit with a low trajectory path is to call it “flat”.  This does not mean, however, it is hit faster with more power or with a less spin rate than a ball with a steeper trajectory path.

Why It Matters

Very simply, the best players in the world use diagonal spin to add ball velocity, increase                              control and the distance and timing challenges of their opponents.