# Spin: what the wall does to a turning ball 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 three spins **Figure 3. Topspin, backspin and sidespin.** The three kinds of spin. Each is named against the way the ball is travelling (the straight arrow). > Figure 3 in words: Three balls. The first, seen from the side and travelling left, turns with its top going the way it travels: topspin. The second, also travelling left, turns with its top going backward: backspin. The third, seen from above and travelling toward the front wall, turns with its front going to the left: sidespin. Figure 3 shows the three kinds. **Topspin**: the top of the ball turns forward, the way it is travelling. **Backspin**: the top turns backward. **Sidespin**: the ball turns about an up-and-down line, so its front turns to the left or to the right. Most real spin is a mix. ## One rule for the air and the wall > **The rule of thumb.** In the air, a spinning ball bends the way its **front** is turning. Off the wall, it kicks the **other** way. In the air, the spinning surface drags the air with it, and the ball is pushed toward the side its front is turning to. Topspin's front turns down, so a topspin ball dips; backspin's front turns up, so a backspin ball floats. At the wall, the front of the ball is the part that touches. The wall grips that face and pushes against the way it is moving. A topspin ball's front face is moving down, so the wall pushes the ball **up**. A backspin ball's front face is moving up, so the wall pushes it **down**. ## Topspin and backspin off the front wall **Figure 4. Topspin, no spin and backspin off the front wall.** Seen from the side (heights drawn five times taller than they are, so the angles show; only the last few feet of the arrival are drawn). Same arrival, three spins, worked out with the model. Without air, all three arrive along the same path; in real play topspin would also bend the ball down on the way in. > Figure 4 in words: Seen from the side, the front wall on the left. Three balls meet the wall at the same spot, 1.5 feet up and 3 degrees downward, at 60 feet a second. With topspin the ball leaves rising, about 6 degrees up, and first lands about 20 feet out. With no spin it leaves about 3 degrees down and lands about 10 feet out. With backspin it leaves about 11 degrees down and lands about 6 feet out. Figure 4 shows three balls meeting the front wall at the same spot, 1.5 feet up and 3° downward. With no spin the ball leaves about 3° downward and first lands about 10 feet out. With topspin it leaves **rising**, about 6° up, and lands about 20 feet out. With backspin it leaves about 11° down and lands about 6 feet out. So it is not quite right that topspin keeps a ball low off the front wall. Topspin does bring the ball down **on the way in**, so it can meet the wall lower and steeper than you aimed. But **at the wall** its spin lifts it, and it carries farther. A backspin ball is the one the front wall pulls down, which is why a cut-under touch shot tends to die near the wall. How big each effect is depends on how much spin there is, how fast the ball is going and how hard the wall grips; the direction does not. ## Topspin becomes backspin **Figure 5. The same turn, the other way round.** The wall sends the ball back but leaves it turning the same way (a little slower). Measured against its new direction, topspin has become backspin. > Figure 5 in words: Seen from the side, the front wall on the left. A ball travels left toward the wall with its top turning toward the wall: topspin. After the wall it travels right, still turning the same way, so its top now turns against its travel: backspin. The wall turns the ball round, but it does not stop it turning. With a strong spin the ball leaves turning the same way it arrived, a little slower. Because it is now travelling the other way, the same turn is the opposite spin (Figure 5): **topspin into the front wall comes out as backspin, and backspin comes out as topspin**. That matters at the next bounce, on the floor. The floor grips the underside of the ball just as the wall grips its front: - **Topspin at the floor** (what a backspin shot carries off the front wall) makes the ball skid on, lower and faster. - **Backspin at the floor** (what a topspin shot carries off the front wall) makes it check up: slower along the floor and sitting up higher. - This is strongest when the ball comes down fairly steeply. A ball that skims in very flat slides through the bounce, and its spin matters less. ## A ball with no spin comes off spinning A ball that meets a wall at an angle has its surface dragged along the wall. The grip slows its run and sets it turning, so it leaves **rolling** along the wall, as if it had rolled a little way along it. That new spin then acts at the next wall or the floor, which is why a ball that has touched a side wall can come off the front wall or the floor a little differently from one that has not. ## Sidespin **Figure 6. Sidespin: bends one way, kicks the other.** Seen from above. The bend in the air is drawn by hand to show its direction; the exit off the wall is worked out with the model, for the ball arriving at the angle drawn. > Figure 6 in words: Seen from above, the front wall at the top. A ball with its front turning left bends left on its way to the front wall. A dashed line shows the mirror exit, carrying on to the left. The worked-out exit kicks to the right of the mirror line instead. Sidespin follows the same rule (Figure 6). A ball whose front is turning left bends left in the air, then the front wall grips that face and kicks the ball to the **right** of where the mirror line would send it. Front turning right: bends right, kicks left. Sidespin does to a **side wall** what topspin and backspin do to the front wall, because the side wall meets the ball on the side that is turning forward or back. On the **floor**, pure sidespin has almost nothing to grip, since the spin is about an up-and-down line. A real hook usually still breaks off the floor because its spin axis leans: part of the turn is about the line the ball is travelling along, and the floor grips that part and kicks the ball sideways. Which way it breaks depends on how the player leans the spin. ## Corners Two walls in a row add up. The first wall sets the ball spinning; the second wall grips that spin. See the pinch on the [worked shots](https://handball.theperfectship.com/guide/angles/shots.md) page. Next: [the hand](https://handball.theperfectship.com/guide/angles/hand.md), where the spin starts. Part of the angles guide: https://handball.theperfectship.com/guide/angles.md