diff --git a/check.js b/check.js
new file mode 100644
index 0000000..0fb3b93
--- /dev/null
+++ b/check.js
@@ -0,0 +1,44 @@
+
+
+document.getElementById('angle').addEventListener('input', function () {
+    const angleInput = this;
+    const angleValue = parseFloat(angleInput.value);
+
+    
+
+    if (angleValue < 0 || angleValue > 90) {
+        angleInput.setCustomValidity("Please enter a value between 0 and 90 degrees.");
+    } else {
+        angleInput.setCustomValidity("");
+    }
+
+    angleInput.reportValidity();
+});
+
+document.getElementById('mass').addEventListener('input', function () {
+    const massInput = this;
+    const massValue = parseFloat(massInput.value);
+
+    if (massValue < 0.1) {
+        massInput.setCustomValidity("Please enter a mass of at least 0.1 kg.");
+    } else {
+        massInput.setCustomValidity("");
+    }
+
+    massInput.reportValidity();
+});
+
+
+document.getElementById('force').addEventListener('input', function () {
+    const forceInput = this;
+    const forceValue = parseFloat(forceInput.value);
+
+    if (forceValue < 1) {
+        forceInput.setCustomValidity("Please enter a force of at least 1 Newton.");
+    } else {
+        forceInput.setCustomValidity("");
+    }
+
+    forceInput.reportValidity();
+});
+
diff --git a/index.html b/index.html
index 5ee5457..1235364 100644
--- a/index.html
+++ b/index.html
@@ -62,6 +62,7 @@ <h3>Range</h3>
         </div>
       </div>
     </div>
+    <script src="check.js"></script>
     <script src="./projectile.js"></script>
     <script src="./visulize.js"></script>
     <script src="./script.js"></script>