From c3904bc3af74e6b6f5b17018c6533520747d73d9 Mon Sep 17 00:00:00 2001
From: nickzerjeski <nick@zerjeski.de>
Date: Mon, 13 Apr 2026 10:50:49 +0200
Subject: [PATCH] feat: add delta x motion equation implementation

Fixes: #191
---
 maths/delta_x.rb      | 11 +++++++++++
 maths/delta_x_test.rb | 18 ++++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 maths/delta_x.rb
 create mode 100644 maths/delta_x_test.rb

diff --git a/maths/delta_x.rb b/maths/delta_x.rb
new file mode 100644
index 0000000..b58fd6f
--- /dev/null
+++ b/maths/delta_x.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+# Computes displacement from uniformly accelerated motion:
+# delta_x = v0 * t + 0.5 * a * t^2
+class DeltaX
+  class << self
+    def call(initial_velocity:, time:, acceleration:)
+      (initial_velocity * time) + (0.5 * acceleration * time * time)
+    end
+  end
+end
diff --git a/maths/delta_x_test.rb b/maths/delta_x_test.rb
new file mode 100644
index 0000000..424c784
--- /dev/null
+++ b/maths/delta_x_test.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+require 'minitest/autorun'
+require_relative './delta_x'
+
+class DeltaXTest < Minitest::Test
+  def test_zero_acceleration
+    assert_in_delta 15.0, DeltaX.call(initial_velocity: 3.0, time: 5.0, acceleration: 0.0), 1E-12
+  end
+
+  def test_positive_acceleration
+    assert_in_delta 20.0, DeltaX.call(initial_velocity: 2.0, time: 4.0, acceleration: 1.5), 1E-12
+  end
+
+  def test_negative_acceleration
+    assert_in_delta 2.0, DeltaX.call(initial_velocity: 5.0, time: 2.0, acceleration: -4.0), 1E-12
+  end
+end