Player guide
Angles: how the ball really comes off the wall
It is natural to think a ball comes off a wall at the same angle it went in. It nearly does, but not quite, and spin can change it a lot. This guide explains why, and how to aim for it.
What you expect, and what usually happens
| What you might expect | What usually happens | Why |
|---|---|---|
| The ball comes off at the mirror angle. | A dead ball, or any ball hit very hard, comes off flatter. A lively ball hit gently and arriving fairly square comes off a little squarer. | The ball loses push-out speed (the bounce factor) and the wall grips it along its surface. Which wins decides it. The wall |
| The ball keeps its speed off the wall. | It always comes off slower, and slower still off a hard hit or a dead ball. | The ball squashes and does not spring all the way back. The wall |
| Topspin keeps a front-wall shot low. | Topspin bends the ball down in the air, but the front wall kicks it up: it comes off higher and carries farther. Backspin is pulled down and lands nearer. | The wall grips the face of the ball that touches it and pushes the other way to its turn. Spin |
| Spin carries on as it was. | The ball keeps turning the same way, but it now travels the other way: topspin becomes backspin for the next bounce, and backspin becomes topspin. | The direction reverses; the turn does not. Spin |
| Sidespin keeps bending the ball the same way. | It bends one way in the air and kicks the other way off the front wall. | Air pushes toward the side the front is turning to; the wall pushes against it. Spin |
| A ball with no spin leaves the wall with none. | A ball that arrives at an angle comes off spinning, rolling along the wall. | The grip that slows its run along the wall also turns it. Spin |
| A pinch (side wall, then front wall) follows the mirror path. | It comes off the front wall slower and cutting more sharply across the court. | The side wall sets it spinning, and the front wall grips that spin. Worked shots |
| The stroke (overhand, sidearm, underhand) sets the spin. | The hand's path through the ball, and where on the ball you meet it, set the spin. The stroke only makes some paths more likely. | The ball turns the way your hand drags its surface. The hand |
| The same aim point gives the same result from any height. | A ball struck from high up arrives steeper, lands nearer the wall and bounces higher. | It comes off the wall heading down more steeply. The hand |
Contents
The wall
A real ball loses speed off the wall and is gripped by it. The two pull the exit angle in opposite directions.
Spin
A spinning ball meets the wall with its surface already moving. The wall pushes against that motion, which can change the exit angle by more than everything on the wall page.
The hand
Your hand is a surface too. The spin a ball carries comes from how your hand drags across it, and where on the ball you meet it.
Worked shots
Four common shots, each with what you might expect, what the ball usually does instead, and how to adjust.
The numbers
Every exit line and number in this guide comes from one small, standard model of a ball bouncing with friction. Here is what it assumes and what it leaves out.
The words this guide uses
- Arrival angle: the angle between the ball's path and the wall as it comes in. 90° is straight in; a small angle is a glancing ball.
- Exit angle: the same angle as the ball leaves.
- Mirror angle: an exit angle equal to the arrival angle, the "angle in equals angle out" rule.
- Flatter means a smaller exit angle, closer to running along the wall. Squarer means a larger one, closer to straight out.
- Bounce factor: the share of its push-out speed (its speed straight into the wall) the ball keeps when it comes off. 1 would be a perfect bounce; a real ball is less.
- Grip: the wall's friction along its surface. A ball can slide all the way through the contact, or the grip can stop the sliding and the ball rolls off the wall.
- Topspin, backspin, sidespin: named against the way the ball is travelling (Figure 3, on the spin page). The front of the ball is the side facing where it is going.
A note on the game
The game keeps a simpler version of this. A cut shot spins: it bends in the air, gets a small push off each wall in the same direction this guide describes, and hops, runs on or checks up off the floor. But each wall and the floor take away a set share of the ball's speed along them, rather than working out the grip from how the ball is spinning, and a ball struck without a cut never picks up spin from a wall. Where the two differ, this guide describes real play, not the game.