Third Law
by TuffetSpider
Third Law makes items and projectiles push the thrower back when they are launched, a joke on Newton's third law of motion for Minecraft.
What it does
Throwing an item or shooting a projectile sends the player backwards with a force the game never applies in reality. The knockback applies to most unstackable items and projectiles, and the values can be set per item, so modded items with non-default values can be handled through a datapack.
Three gamerules control the effect: one turns item knockback on or off, one turns projectile knockback on or off, and one decides whether the effect applies in the air. Projectile knockback also reaches mobs such as pillagers, blazes and skeletons, so their shots can push them as well.
Third Law runs on Fabric and needs Fabric API. Players join without it, since only the server has to run the mod. Files are published for 1.21.1 only, with 1.0.0 as the latest file from 2024-12-07, and the code is licensed as All rights reserved, so it is not open source.
Key features
Backward throws
Items thrown and projectiles shot push the thrower in the opposite direction of travel.
Per-item knockback values
Unstackable items and projectiles get custom values, and most other items use a non-default value.
Datapack support
Modded blocks and items can be given their own knockback values through a datapack.
Gamerule controls
Three gamerules toggle item knockback, projectile knockback and whether the effect works while airborne.
Mob projectile knockback
Projectiles hitting pillagers, blazes and skeletons push those mobs back as well.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Who it’s for: Server owners who want a lighthearted physics change, and pack makers who add modded items and want them to push the player in the same way.
How it compares
Projectile Knockback is a Fabric server-side mod for 1.21 – 1.21.8, open source under the GNU General Public License v3.0 only, so it covers a narrower version range than Third Law. G-Forces is a client-side Fabric mod for 1.21.11, open source under the MIT License, so it works only on the client. Axe Throw is a Fabric mod for 1.21.1 that needs both the client and the server, released under the MIT-0 license and not open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Third Law | Fabric | 1.21.1 | Server-side only | 2024-12-07 |
| Projectile Knockback | Fabric | 1.21 – 1.21.8 | Server-side only | 2025-09-17 |
| G-Forces | Fabric | 1.21.11 | Client-side only | 2026-07-08 |
| Axe Throw | Fabric | 1.21.1 | Client and server | 2026-07-17 |
Questions
Does Third Law need Fabric API?
Does every player need Third Law installed?
Can the knockback be turned off?
Which Minecraft versions does Third Law support?
In the catalog
Third Law is one of 3,932 Transportation mods on ModsFinder, and one of 2,390 Transportation mods for Fabric. 32,366 mods support Minecraft 1.21.1.
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What the author says
This mod makes it so when you throw items or shoot projectiles, it throws you backwards! Most unstackable items as well as projectiles have custom values, but most other items do not have a non-default value! This should be datapackable, so if you'd like to do that, or add modded blocks/items that have non-default…
Official listing
- Modrinth page
- modrinth.com/mod/third-law
- Owner
- TuffetSpider
- Published
- 2024-12-07
- Updated on Modrinth
- 2024-12-07
- Facts verified
- 2026-10-15