diff --git a/src/c/funktionen.c b/src/c/funktionen.c
index 1b33bb3..8a5efbe 100644
--- a/src/c/funktionen.c
+++ b/src/c/funktionen.c
@@ -327,4 +327,8 @@ float average(float x, float y) {
 // Function to calculate the remainder of division between two numbers
 float remainderValue(float x, float y) {
     return fmod(x, y);
+}
+
+float f(float m) {
+    return m * 9.81;
 }
\ No newline at end of file
diff --git a/src/c/funktionen.h b/src/c/funktionen.h
index 5958b04..7cdc807 100644
--- a/src/c/funktionen.h
+++ b/src/c/funktionen.h
@@ -151,4 +151,7 @@ float average(float x, float y);
 // Function to calculate the remainder of division between two numbers
 float remainderValue(float x, float y);
 
+float f(float m);
+// berechnet die Gewichtkraft
+
 #endif
\ No newline at end of file
diff --git a/src/test/test_funktionen.c b/src/test/test_funktionen.c
index 6f2966b..4094322 100644
--- a/src/test/test_funktionen.c
+++ b/src/test/test_funktionen.c
@@ -424,4 +424,18 @@ void test_tangentDegrees(void) {
     // Add more test cases for different inputs and expected outputs
 }
 
+void test_weight_at_mass100(void)
+{
+    /* arrange */
+    float actual;
+    float expected = 981;
+
+    /* act */;
+    float m = 100;
+    actual = f(m);
+
+    /* assert */
+    TEST_ASSERT_EQUAL_FLOAT(expected, actual);
+}
+
 #endif
\ No newline at end of file