diff --git a/packages/pinball_components/lib/src/components/bumping_behavior.dart b/packages/pinball_components/lib/src/components/bumping_behavior.dart
index 17931838..0d259860 100644
--- a/packages/pinball_components/lib/src/components/bumping_behavior.dart
+++ b/packages/pinball_components/lib/src/components/bumping_behavior.dart
@@ -7,7 +7,9 @@ import 'package:pinball_flame/pinball_flame.dart';
 /// {@endtemplate}
 class BumpingBehavior extends ContactBehavior {
   /// {@macro bumping_behavior}
-  BumpingBehavior({required double strength}) : _strength = strength;
+  BumpingBehavior({required double strength})
+      : assert(strength >= 0, "Strength can't be negative."),
+        _strength = strength;
 
   /// Determines how strong the bump is.
   final double _strength;
diff --git a/packages/pinball_components/lib/src/components/plunger/behaviors/plunger_pulling_behavior.dart b/packages/pinball_components/lib/src/components/plunger/behaviors/plunger_pulling_behavior.dart
index c7188aeb..db6bcaa3 100644
--- a/packages/pinball_components/lib/src/components/plunger/behaviors/plunger_pulling_behavior.dart
+++ b/packages/pinball_components/lib/src/components/plunger/behaviors/plunger_pulling_behavior.dart
@@ -7,7 +7,8 @@ class PlungerPullingBehavior extends Component
     with FlameBlocReader<PlungerCubit, PlungerState> {
   PlungerPullingBehavior({
     required double strength,
-  }) : _strength = strength;
+  })  : assert(strength >= 0, "Strength can't be negative."),
+        _strength = strength;
 
   final double _strength;
 
@@ -22,7 +23,7 @@ class PlungerPullingBehavior extends Component
   @override
   void update(double dt) {
     if (bloc.state.isPulling) {
-      _plunger.body.linearVelocity = Vector2(0, _strength.abs());
+      _plunger.body.linearVelocity = Vector2(0, _strength);
     }
   }
 }
diff --git a/packages/pinball_components/lib/src/components/plunger/behaviors/plunger_releasing_behavior.dart b/packages/pinball_components/lib/src/components/plunger/behaviors/plunger_releasing_behavior.dart
index ac02984f..d2935818 100644
--- a/packages/pinball_components/lib/src/components/plunger/behaviors/plunger_releasing_behavior.dart
+++ b/packages/pinball_components/lib/src/components/plunger/behaviors/plunger_releasing_behavior.dart
@@ -6,7 +6,8 @@ class PlungerReleasingBehavior extends Component
     with FlameBlocListenable<PlungerCubit, PlungerState> {
   PlungerReleasingBehavior({
     required double strength,
-  }) : _strength = strength;
+  })  : assert(strength >= 0, "Strength can't be negative."),
+        _strength = strength;
 
   final double _strength;
 
@@ -22,8 +23,8 @@ class PlungerReleasingBehavior extends Component
   void onNewState(PlungerState state) {
     super.onNewState(state);
     if (state.isReleasing) {
-      final velocity = (_plunger.initialPosition.y - _plunger.body.position.y) *
-          _strength.abs();
+      final velocity =
+          (_plunger.initialPosition.y - _plunger.body.position.y) * _strength;
       _plunger.body.linearVelocity = Vector2(0, velocity);
     }
   }
diff --git a/packages/pinball_components/test/src/components/bumping_behavior_test.dart b/packages/pinball_components/test/src/components/bumping_behavior_test.dart
index 07e35cca..7a87a46c 100644
--- a/packages/pinball_components/test/src/components/bumping_behavior_test.dart
+++ b/packages/pinball_components/test/src/components/bumping_behavior_test.dart
@@ -24,6 +24,20 @@ void main() {
   final flameTester = FlameTester(TestGame.new);
 
   group('BumpingBehavior', () {
+    test('can be instantiated', () {
+      expect(
+        BumpingBehavior(strength: 0),
+        isA<BumpingBehavior>(),
+      );
+    });
+
+    test('throws assertion error when strength is negative ', () {
+      expect(
+        () => BumpingBehavior(strength: -1),
+        throwsAssertionError,
+      );
+    });
+
     flameTester.test('can be added', (game) async {
       final behavior = BumpingBehavior(strength: 0);
       final component = _TestBodyComponent();
diff --git a/packages/pinball_components/test/src/components/plunger/behaviors/plunger_pulling_behavior_test.dart b/packages/pinball_components/test/src/components/plunger/behaviors/plunger_pulling_behavior_test.dart
index 4f789aa5..4eec7029 100644
--- a/packages/pinball_components/test/src/components/plunger/behaviors/plunger_pulling_behavior_test.dart
+++ b/packages/pinball_components/test/src/components/plunger/behaviors/plunger_pulling_behavior_test.dart
@@ -42,6 +42,13 @@ void main() {
       );
     });
 
+    test('throws assertion error when strength is negative ', () {
+      expect(
+        () => PlungerPullingBehavior(strength: -1),
+        throwsAssertionError,
+      );
+    });
+
     flameTester.test('can be loaded', (game) async {
       final behavior = PlungerPullingBehavior(strength: 0);
       await game.pump(behavior);
diff --git a/packages/pinball_components/test/src/components/plunger/behaviors/plunger_releasing_behavior_test.dart b/packages/pinball_components/test/src/components/plunger/behaviors/plunger_releasing_behavior_test.dart
index 77d70380..501753c4 100644
--- a/packages/pinball_components/test/src/components/plunger/behaviors/plunger_releasing_behavior_test.dart
+++ b/packages/pinball_components/test/src/components/plunger/behaviors/plunger_releasing_behavior_test.dart
@@ -40,6 +40,13 @@ void main() {
       );
     });
 
+    test('throws assertion error when strength is negative ', () {
+      expect(
+        () => PlungerReleasingBehavior(strength: -1),
+        throwsAssertionError,
+      );
+    });
+
     flameTester.test('can be loaded', (game) async {
       final behavior = PlungerReleasingBehavior(strength: 0);
       await game.pump(behavior);