diff --git a/src/Aufgabe5Test.java b/src/Aufgabe5Test.java
index e188c1e..cd67d81 100644
--- a/src/Aufgabe5Test.java
+++ b/src/Aufgabe5Test.java
@@ -6,29 +6,27 @@ public class Aufgabe5Test {
 
     @Test
     public void testEP2() {
-        /* //TODO: uncomment for testing
-
         //test classes NamedBody and MassiveForceHashMap
 
         // create 12 named bodies
         NamedBody sun1, mercury1, venus1, earth1, moon1, mars1, deimos1, phobos1, vesta1, pallas1, hygiea1, ceres1;
 
         // create a nameless body
-        Body earth2 = new Body(5.972E24, new Vector3(-6.13135922534815E10, -1.383789852227691E11, 2.719682263474911E7), new Vector3(26832.720535473603, -11948.23168764519, 1.9948243075997851));
+        Body earth2 = new Body(SolSystem4.EARTH);
 
         // create the same 12 named body-force pairs
-        sun1 = new NamedBody("Sun", 1.989E30, new Vector3(0.0, 0.0, 0.0), new Vector3(0.0, 0.0, 0.0));
-        earth1 = new NamedBody("Earth", 5.972E24, new Vector3(-6.13135922534815E10, -1.383789852227691E11, 2.719682263474911E7), new Vector3(26832.720535473603, -11948.23168764519, 1.9948243075997851));
-        moon1 = new NamedBody("Moon", 7.349E22, new Vector3(-6.132484773775896E10, -1.387394951280871E11, 1.701046736294776E7), new Vector3(27916.62329282941, -12020.39526008238, -94.89703264508708));
-        mars1 = new NamedBody("Mars", 6.41712E23, new Vector3(-1.7923193702925848E11, 1.726665823982123E11, 7.991673845249474E9), new Vector3(-15925.78496403673, -15381.16179928219, 68.67560910598857));
-        deimos1 = new NamedBody("Deimos", 1.8E20, new Vector3(-1.792255010450533E11, 1.726891122683271E11, 7.990659337380297E9), new Vector3(-17100.476719804457, -15020.348656808, 631.2927851249581));
-        phobos1 = new NamedBody("Phobos", 1.08E20, new Vector3(-1.792253482539647E11, 1.72661109673625E11, 7.987848354800322E9), new Vector3(-14738.203714241401, -13671.17675223948, -411.0012490555253));
-        mercury1 = new NamedBody("Mercury", 3.301E23, new Vector3(-5.167375560011926E10, -4.217574885682655E10, 1.14808913958168E9), new Vector3(21580.25398577148, -34951.03632847389, -4835.225596525241));
-        venus1 = new NamedBody("Venus", 4.86747E24, new Vector3(-3.123150865740532E10, 1.0395568504115701E11, 3.173401325838074E9), new Vector3(-33748.180519629335, -10014.25141045021, 1809.94488874165));
-        vesta1 = new NamedBody("Vesta", 2.5908E20, new Vector3(-3.337493557929893E11, -4.7147908276077385E10, 4.1923010146878105E10), new Vector3(4440.54247538484, -19718.49074006637, 48.06573124543601));
-        pallas1 = new NamedBody("Pallas", 2.14E20, new Vector3(4.3452066613895575E11, -2.057319365171432E11, 1.0549957423213101E11), new Vector3(5058.947582097117, 11184.45711782372, -8183.524138259704));
-        hygiea1 = new NamedBody("Hygiea", 8.32E19, new Vector3(-3.983943433707043E11, 2.325833000024021E11, -2.233667695713672E10), new Vector3(-6931.864585548552, -15686.8108598699, -690.5791992347208));
-        ceres1 = new NamedBody("Ceres", 9.394E20, new Vector3(3.781372641419032E11, 1.96718960466285E11, -6.366459168068592E10), new Vector3(-8555.324226752316, 14718.33755980907, 2040.230135060142));
+        sun1 = new NamedBody(SolSystem4.SUN_NAMED);
+        earth1 = new NamedBody(SolSystem4.EARTH_NAMED);
+        moon1 = new NamedBody(SolSystem4.MOON_NAMED);
+        mars1 = new NamedBody(SolSystem4.MARS_NAMED);
+        deimos1 = new NamedBody(SolSystem4.DEIMOS_NAMED);
+        phobos1 = new NamedBody(SolSystem4.PHOBOS_NAMED);
+        mercury1 = new NamedBody(SolSystem4.MERCURY_NAMED);
+        venus1 = new NamedBody(SolSystem4.VENUS_NAMED);
+        vesta1 = new NamedBody(SolSystem4.VESTA_NAMED);
+        pallas1 = new NamedBody(SolSystem4.PALLAS_NAMED);
+        hygiea1 = new NamedBody(SolSystem4.HYGIEA_NAMED);
+        ceres1 = new NamedBody(SolSystem4.CERES_NAMED);
 
         NamedBody sun2 = new NamedBody("Sun", 1.9895E30, new Vector3(0.1, 0.0, 0.0), new Vector3(0.0, 0.0, 0.0));
         NamedBody earth3 = new NamedBody("Earth", 1, new Vector3(0, 0, 0), new Vector3(0, 0, 0));
@@ -68,11 +66,16 @@ public class Aufgabe5Test {
         assertFalse(map.containsKey(new Body(0, new Vector3(0, 0, 0), new Vector3(0, 0, 0))));
         assertFalse(map.containsKey(new NamedBody("Omuamua", 0, new Vector3(0, 0, 0), new Vector3(0, 0, 0))));
 
+        int hashCode1 = map.hashCode();
+
         Vector3 f = new Vector3(5, 5, 5);
         map.put(earth3, f);
         assertEquals(f, map.get(earth1));
         assertNull(map.get(earth2));
 
-        */ //TODO: uncomment
+        int hashCode2 = map.hashCode();
+        assertEquals(map, map);
+        assertEquals(hashCode2, map.hashCode());
+        assertNotEquals(hashCode1, hashCode2);
     }
 }
diff --git a/src/Body.java b/src/Body.java
index f5ab255..abf74b4 100644
--- a/src/Body.java
+++ b/src/Body.java
@@ -3,7 +3,7 @@ import codedraw.CodeDraw;
 /**
  * This class represents celestial bodies like stars, planets, asteroids, etc...
  */
-public class Body {
+public class Body implements Massive {
     private final double mass;
     private Vector3 massCenter; // position of the mass center.
     private Vector3 currentMovement;
diff --git a/src/BodyLinkedList.java b/src/BodyLinkedList.java
index e568efe..36fdc52 100644
--- a/src/BodyLinkedList.java
+++ b/src/BodyLinkedList.java
@@ -171,11 +171,8 @@ public class BodyLinkedList implements Iterable<Body> {
         }
 
         Item item = first;
-        for (int i = 0; i < size; i++) {
-            if (item.body == body) {
-                return i;
-            }
-            item = item.next;
+        for (int i = 0; i < size; i++, item = item.next) {
+            if (item.body == body) return i;
         }
 
         return -1;
@@ -217,9 +214,9 @@ public class BodyLinkedList implements Iterable<Body> {
             public Body next() {
                 if (!yieldedFirst) {
                     yieldedFirst = true;
-                    return ptr.body;
+                } else {
+                    ptr = ptr.next;
                 }
-                ptr = ptr.next;
                 return ptr.body;
             }
         };
diff --git a/src/MassiveForceHashMap.java b/src/MassiveForceHashMap.java
index ac1818d..27cbe4e 100644
--- a/src/MassiveForceHashMap.java
+++ b/src/MassiveForceHashMap.java
@@ -3,14 +3,21 @@
  * exerted on the object). The number of key-value pairs is not limited.
  */
 public class MassiveForceHashMap {
-
-    // TODO: define missing parts of this class.
+    private int size;
+    private Massive[] keys;
+    private Vector3[] values;
 
     /**
      * Initializes 'this' as an empty map.
      */
     public MassiveForceHashMap() {
-        // TODO: implement constructor.
+        this(16);
+    }
+
+    public MassiveForceHashMap(int capacity) {
+        this.size = 0;
+        this.keys = new Massive[capacity];
+        this.values = new Vector3[capacity];
     }
 
     /**
@@ -19,8 +26,37 @@ public class MassiveForceHashMap {
      * Precondition: key != null.
      */
     public Vector3 put(Massive key, Vector3 value) {
-        // TODO: implement method.
-        return null;
+        if (size > keys.length / 2) doubleCapacity();
+
+        int idx = ((key.hashCode() % keys.length) + keys.length) % keys.length;
+        for (int i = 0; i < keys.length; i++) {
+            int pos = (idx + i) % keys.length;
+            if (values[pos] == null) {
+                keys[pos] = key;
+                values[pos] = value;
+                size++;
+                return null;
+            } else if (keys[pos].equals(key)) {
+                Vector3 old = values[pos];
+                values[pos] = value;
+                return old;
+            }
+        }
+        throw new RuntimeException();
+    }
+
+    private void doubleCapacity() {
+        Massive[] oldKeys = keys;
+        Vector3[] oldValues = values;
+        keys = new Massive[keys.length * 2];
+        values = new Vector3[values.length * 2];
+        size = 0;
+
+        for (int i = 0; i < oldKeys.length; i++) {
+            Massive k = oldKeys[i];
+            Vector3 v = oldValues[i];
+            if (v != null) put(k, v);
+        }
     }
 
     /**
@@ -29,7 +65,15 @@ public class MassiveForceHashMap {
      * Precondition: key != null.
      */
     public Vector3 get(Massive key) {
-        // TODO: implement method.
+        int idx = ((key.hashCode() % keys.length) + keys.length) % keys.length;
+        for (int i = 0; i < keys.length; i++) {
+            int pos = (idx + i) % keys.length;
+            if (keys[pos] == null) {
+                break;
+            } else if (keys[pos].equals(key)) {
+                return values[pos];
+            }
+        }
         return null;
     }
 
@@ -37,17 +81,32 @@ public class MassiveForceHashMap {
      * Returns 'true' if this map contains a mapping for the specified key.
      */
     public boolean containsKey(Massive key) {
-        // TODO: implement method.
-        return false;
+        return this.get(key) != null;
     }
 
     /**
      * Returns a readable representation of this map, with all key-value pairs. Their order is not
      * defined.
      */
+    @Override
     public String toString() {
-        // TODO: implement method.
-        return "";
+        if (size == 0) return "{}";
+
+        StringBuilder sb = new StringBuilder("{");
+        for (int i = 0; i < keys.length; i++) {
+            Massive k = keys[i];
+            Vector3 v = values[i];
+            if (k != null && v != null) {
+                sb.append("\n  ");
+                sb.append(k);
+                sb.append(": ");
+                sb.append(v);
+                sb.append(",");
+            }
+        }
+        sb.deleteCharAt(sb.length() - 1);
+        sb.append("\n}");
+        return sb.toString();
     }
 
     /**
@@ -57,24 +116,46 @@ public class MassiveForceHashMap {
      * key-value pair in `this` equals one key-value pair in `o`. Two key-value pairs are
      * equal if the two keys are equal and the two values are equal. Otherwise, `false` is returned.
      */
+    @Override
     public boolean equals(Object o) {
-        // TODO: implement method.
-        return false;
+        if (!(o instanceof MassiveForceHashMap map) || map.size != size)
+            return false;
+
+        for (int i = 0; i < keys.length; i++) {
+            Massive k1 = keys[i];
+            Vector3 v1 = values[i];
+            if (k1 == null || v1 == null) continue;
+            Vector3 v2 = map.get(k1);
+            if (!v1.equals(v2)) return false;
+        }
+        return true;
     }
 
     /**
      * Returns the hashCode of `this`.
      */
+    @Override
     public int hashCode() {
-        //TODO: implement method.
-        return 0;
+        int hash = 0;
+        for (int i = 0; i < keys.length; i++) {
+            Massive k = keys[i];
+            Vector3 v = values[i];
+            if (k == null || v == null) continue;
+            hash ^= k.hashCode();
+            hash ^= v.hashCode();
+        }
+        return hash;
     }
 
     /**
      * Returns a list of all the keys in no specified order.
      */
     public MassiveLinkedList keyList() {
-        // TODO: implement method.
-        return null;
+        MassiveLinkedList list = new MassiveLinkedList();
+        for (int i = 0; i < keys.length; i++) {
+            if (keys[i] != null && values[i] != null)
+                list.addLast(keys[i]);
+        }
+        return list;
     }
 }
diff --git a/src/MassiveLinkedList.java b/src/MassiveLinkedList.java
index c6834fe..71f800e 100644
--- a/src/MassiveLinkedList.java
+++ b/src/MassiveLinkedList.java
@@ -1,16 +1,20 @@
+import java.util.Iterator;
+
 /**
  * A list of massive objects implemented as a linked list.
  * The number of elements of the list is not limited.
  */
-public class MassiveLinkedList {
-
-    //TODO: declare variables.
+public class MassiveLinkedList implements Iterable<Massive> {
+    private int size = 0;
+    private Item first;
+    private Item last;
 
     /**
      * Initializes 'this' as an empty list.
      */
     public MassiveLinkedList() {
-        //TODO: define constructor.
+        first = null;
+        last = null;
     }
 
     /**
@@ -20,21 +24,38 @@ public class MassiveLinkedList {
      * Precondition: list != null.
      */
     public MassiveLinkedList(BodyLinkedList list) {
-        //TODO: define constructor.
+        this.size = 0;
+        for (Body b : list) {
+            this.addLast(b);
+        }
     }
 
     /**
      * Inserts the specified element 'body' at the beginning of this list.
      */
     public void addFirst(Massive body) {
-        //TODO: implement method.
+        if (first == null) {
+            first = new Item(body);
+            last = first;
+        } else {
+            first.setPrev(new Item(body));
+            first = first.prev;
+        }
+        size++;
     }
 
     /**
      * Appends the specified element 'body' to the end of this list.
      */
     public void addLast(Massive body) {
-        //TODO: implement method.
+        if (last == null) {
+            last = new Item(body);
+            first = last;
+        } else {
+            last.setNext(new Item(body));
+            last = last.next;
+        }
+        size++;
     }
 
     /**
@@ -42,8 +63,7 @@ public class MassiveLinkedList {
      * Returns 'null' if the list is empty.
      */
     public Massive getLast() {
-        //TODO: implement method.
-        return null;
+        return (last != null) ? last.body : null;
     }
 
     /**
@@ -51,8 +71,7 @@ public class MassiveLinkedList {
      * Returns 'null' if the list is empty.
      */
     public Massive getFirst() {
-        //TODO: implement method.
-        return null;
+        return (first != null) ? first.body : null;
     }
 
     /**
@@ -60,8 +79,14 @@ public class MassiveLinkedList {
      * Returns 'null' if the list is empty.
      */
     public Massive pollFirst() {
-        //TODO: implement method.
-        return null;
+        if (first == null) {
+            return null;
+        }
+        Massive m = first.body;
+        first = first.next;
+        if (first != null) first.setPrev(null);
+        size--;
+        return m;
     }
 
     /**
@@ -69,8 +94,14 @@ public class MassiveLinkedList {
      * Returns 'null' if the list is empty.
      */
     public Massive pollLast() {
-        //TODO: implement method.
-        return null;
+        if (last == null) {
+            return null;
+        }
+        Massive m = last.body;
+        last = last.next;
+        if (last != null) last.setNext(null);
+        size--;
+        return m;
     }
 
     /**
@@ -78,7 +109,22 @@ public class MassiveLinkedList {
      * Precondition: i >= 0 && i <= size().
      */
     public void add(int i, Massive m) {
-        //TODO: implement method.
+        if (first == null || i == 0) {
+            addFirst(m);
+            return;
+        } else if (i == size) {
+            addLast(m);
+            return;
+        }
+
+        Item item = first;
+        for (int j = 0; j < i; j++) {
+            item = item.next;
+        }
+
+        item.prev.setNext(new Item(m));
+        item.setPrev(item.prev.next);
+        size++;
     }
 
     /**
@@ -86,8 +132,19 @@ public class MassiveLinkedList {
      * Precondition: i >= 0 && i < size().
      */
     public Massive get(int i) {
-        //TODO: implement method.
-        return null;
+        Item item;
+        if (i < size / 2) {
+            item = first;
+            for (int j = 0; j < i; j++) {
+                item = item.next;
+            }
+        } else {
+            item = last;
+            for (int j = size - 1; j > i; j--) {
+                item = item.prev;
+            }
+        }
+        return item.body;
     }
 
     /**
@@ -95,15 +152,67 @@ public class MassiveLinkedList {
      * this list does not contain the element.
      */
     public int indexOf(Massive m) {
-        //TODO: implement method.
-        return -2;
+        if (first == null) {
+            return -1;
+        }
+
+        Item item = first;
+        for (int i = 0; i < size; i++, item = item.next) {
+            if (item.body.equals(m)) return i;
+        }
+
+        return -1;
     }
 
     /**
      * Returns the number of elements in this list.
      */
     public int size() {
-        //TODO: implement method.
-        return -1;
+        return size;
+    }
+
+    @Override
+    public Iterator<Massive> iterator() {
+        return new Iterator<>() {
+            Item ptr = first;
+            boolean yieldedFirst = false;
+
+            @Override
+            public boolean hasNext() {
+                return ptr != null && (!yieldedFirst || ptr.next != null);
+            }
+
+            @Override
+            public Massive next() {
+                if (!yieldedFirst) {
+                    yieldedFirst = true;
+                } else {
+                    ptr = ptr.next;
+                }
+                return ptr.body;
+            }
+        };
+    }
+
+    private class Item {
+        private final Massive body;
+        private Item prev;
+        private Item next;
+
+        public Item(Massive body) {
+            this.body = body;
+            this.prev = null;
+            this.next = null;
+        }
+
+        public void setPrev(Item prev) {
+            this.prev = prev;
+            if (prev != null) prev.next = this;
+        }
+
+        public void setNext(Item next) {
+            this.next = next;
+            if (next != null) next.prev = this;
+        }
     }
 }
diff --git a/src/NamedBody.java b/src/NamedBody.java
index 8f08592..13e3899 100644
--- a/src/NamedBody.java
+++ b/src/NamedBody.java
@@ -1,46 +1,79 @@
-public class NamedBody /* TODO: add clause(s) */ {
+import codedraw.CodeDraw;
 
-    // TODO: add missing parts of this class.
+public class NamedBody implements Massive {
+
+    private final String name;
+    private final Body body;
 
     /**
-     * Initializes this with name, mass, current position and movement. The associated force
-     * is initialized with a zero vector.
+     * Initializes this with name, mass, current position and movement.
      */
     public NamedBody(String name, double mass, Vector3 massCenter, Vector3 currentMovement) {
-        // TODO: implement constructor.
+        this(name, new Body(mass, massCenter, currentMovement));
+    }
+
+    public NamedBody(String name, Body body) {
+        this.name = name;
+        this.body = body;
+    }
+
+    public NamedBody(NamedBody other) {
+        this(other.name, new Body(other.body));
     }
 
     /**
      * Returns the name of the body.
      */
     public String getName() {
-        // TODO: implement method.
-        return "";
+        return name;
+    }
+
+    public Body getBody() {
+        return body;
+    }
+
+    public Vector3 getMassCenter() {
+        return body.getMassCenter();
+    }
+
+    public double getMass() {
+        return body.getMass();
     }
 
     /**
      * Compares `this` with the specified object. Returns `true` if the specified `o` is not
      * `null` and is of type `NamedBody` and both `this` and `o` have equal names.
-     * Otherwise `false` is returned.
+     * Otherwise, `false` is returned.
      */
+    @Override
     public boolean equals(Object o) {
-        //TODO: implement method.
-        return false;
+        if (!(o instanceof NamedBody b)) return false;
+        return this.name.equals(b.name);
     }
 
     /**
      * Returns the hashCode of `this`.
      */
+    @Override
     public int hashCode() {
-        //TODO: implement method.
-        return 0;
+        return this.name.hashCode();
     }
 
     /**
      * Returns a readable representation including the name of this body.
      */
+    @Override
     public String toString() {
-        //TODO: implement method.
-        return "";
+        return this.getName();
+    }
+
+    @Override
+    public void move(Vector3 force) {
+        body.move(force);
+    }
+
+    @Override
+    public void draw(CodeDraw cd) {
+        body.draw(cd);
     }
 }
diff --git a/src/NamedBodyForcePair.java b/src/NamedBodyForcePair.java
index 5b5820d..b2e0392 100644
--- a/src/NamedBodyForcePair.java
+++ b/src/NamedBodyForcePair.java
@@ -6,8 +6,7 @@ import codedraw.CodeDraw;
  */
 public class NamedBodyForcePair implements CosmicSystem {
 
-    private final String name;
-    private final Body body;
+    private final NamedBody body;
     private final Vector3 force = new Vector3();
 
     /**
@@ -15,27 +14,30 @@ public class NamedBodyForcePair implements CosmicSystem {
      * is initialized with a zero vector.
      */
     public NamedBodyForcePair(String name, double mass, Vector3 massCenter, Vector3 currentMovement) {
-        this(name, new Body(mass, massCenter, currentMovement));
+        this(new NamedBody(name, mass, massCenter, currentMovement));
     }
 
-    public NamedBodyForcePair(String name, Body b) {
-        this.body = b;
-        this.name = name;
+    public NamedBodyForcePair(String name, Body body) {
+        this(new NamedBody(name, body));
+    }
+
+    public NamedBodyForcePair(NamedBody body) {
+        this.body = body;
     }
 
     public NamedBodyForcePair(NamedBodyForcePair other) {
-        this(other.name, new Body(other.body));
+        this(new NamedBody(other.body));
     }
 
     public Body getBody() {
-        return body;
+        return body.getBody();
     }
 
     /**
      * Returns the name of the body.
      */
     public String getName() {
-        return name;
+        return body.getName();
     }
 
     @Override
@@ -70,13 +72,13 @@ public class NamedBodyForcePair implements CosmicSystem {
 
     @Override
     public void addForceTo(CosmicSystem cs) {
-        cs.addForceFrom(body);
+        cs.addForceFrom(body.getBody());
     }
 
     @Override
     public BodyLinkedList getBodies() {
         BodyLinkedList list = new BodyLinkedList();
-        list.addFirst(body);
+        list.addFirst(body.getBody());
         return list;
     }
 
diff --git a/src/Simulation5.java b/src/Simulation5.java
index 2e77e2e..7d08bb7 100644
--- a/src/Simulation5.java
+++ b/src/Simulation5.java
@@ -40,31 +40,74 @@ public class Simulation5 {
         CodeDraw cd = new CodeDraw();
 
         // create solar system with 12 bodies
-        NamedBody sun = new NamedBody("Sun", 1.989E30, new Vector3(0.0, 0.0, 0.0), new Vector3(0.0, 0.0, 0.0));
-        NamedBody earth = new NamedBody("Earth", 5.972E24, new Vector3(-6.13135922534815E10, -1.383789852227691E11, 2.719682263474911E7), new Vector3(26832.720535473603, -11948.23168764519, 1.9948243075997851));
-        NamedBody moon = new NamedBody("Moon", 7.349E22, new Vector3(-6.132484773775896E10, -1.387394951280871E11, 1.701046736294776E7), new Vector3(27916.62329282941, -12020.39526008238, -94.89703264508708));
-        NamedBody mars = new NamedBody("Mars", 6.41712E23, new Vector3(-1.7923193702925848E11, 1.726665823982123E11, 7.991673845249474E9), new Vector3(-15925.78496403673, -15381.16179928219, 68.67560910598857));
-        NamedBody deimos = new NamedBody("Deimos", 1.8E20, new Vector3(-1.792255010450533E11, 1.726891122683271E11, 7.990659337380297E9), new Vector3(-17100.476719804457, -15020.348656808, 631.2927851249581));
-        NamedBody phobos = new NamedBody("Phobos", 1.08E20, new Vector3(-1.792253482539647E11, 1.72661109673625E11, 7.987848354800322E9), new Vector3(-14738.203714241401, -13671.17675223948, -411.0012490555253));
-        NamedBody mercury = new NamedBody("Mercury", 3.301E23, new Vector3(-5.167375560011926E10, -4.217574885682655E10, 1.14808913958168E9), new Vector3(21580.25398577148, -34951.03632847389, -4835.225596525241));
-        NamedBody venus = new NamedBody("Venus", 4.86747E24, new Vector3(-3.123150865740532E10, 1.0395568504115701E11, 3.173401325838074E9), new Vector3(-33748.180519629335, -10014.25141045021, 1809.94488874165));
-        NamedBody vesta = new NamedBody("Vesta", 2.5908E20, new Vector3(-3.337493557929893E11, -4.7147908276077385E10, 4.1923010146878105E10), new Vector3(4440.54247538484, -19718.49074006637, 48.06573124543601));
-        NamedBody pallas = new NamedBody("Pallas", 2.14E20, new Vector3(4.3452066613895575E11, -2.057319365171432E11, 1.0549957423213101E11), new Vector3(5058.947582097117, 11184.45711782372, -8183.524138259704));
-        NamedBody hygiea = new NamedBody("Hygiea", 8.32E19, new Vector3(-3.983943433707043E11, 2.325833000024021E11, -2.233667695713672E10), new Vector3(-6931.864585548552, -15686.8108598699, -690.5791992347208));
-        NamedBody ceres = new NamedBody("Ceres", 9.394E20, new Vector3(3.781372641419032E11, 1.96718960466285E11, -6.366459168068592E10), new Vector3(-8555.324226752316, 14718.33755980907, 2040.230135060142));
-
+        NamedBody sun = new NamedBody(SolSystem4.SUN_NAMED);
+        NamedBody earth = new NamedBody(SolSystem4.EARTH_NAMED);
+        NamedBody moon = new NamedBody(SolSystem4.MOON_NAMED);
+        NamedBody mars = new NamedBody(SolSystem4.MARS_NAMED);
+        NamedBody deimos = new NamedBody(SolSystem4.DEIMOS_NAMED);
+        NamedBody phobos = new NamedBody(SolSystem4.PHOBOS_NAMED);
+        NamedBody mercury = new NamedBody(SolSystem4.MERCURY_NAMED);
+        NamedBody venus = new NamedBody(SolSystem4.VENUS_NAMED);
+        NamedBody vesta = new NamedBody(SolSystem4.VESTA_NAMED);
+        NamedBody pallas = new NamedBody(SolSystem4.PALLAS_NAMED);
+        NamedBody hygiea = new NamedBody(SolSystem4.HYGIEA_NAMED);
+        NamedBody ceres = new NamedBody(SolSystem4.CERES_NAMED);
         // create some additional bodies
         Body[] bodies = new Body[NUMBER_OF_BODIES];
 
         Random random = new Random(2022);
 
         for (int i = 0; i < bodies.length; i++) {
-            bodies[i] = new Body(Math.abs(random.nextGaussian()) * OVERALL_SYSTEM_MASS / bodies.length,
+            bodies[i] = new Body(
+                    Math.abs(random.nextGaussian()) * OVERALL_SYSTEM_MASS / bodies.length,
                     new Vector3(0.2 * random.nextGaussian() * AU, 0.2 * random.nextGaussian() * AU, 0.2 * random.nextGaussian() * AU),
-                    new Vector3(0 + random.nextGaussian() * 5e3, 0 + random.nextGaussian() * 5e3, 0 + random.nextGaussian() * 5e3));
+                    new Vector3(0 + random.nextGaussian() * 5e3, 0 + random.nextGaussian() * 5e3, 0 + random.nextGaussian() * 5e3)
+            );
         }
 
-        //TODO: implementation of this method according to 'Aufgabenblatt5.md'.
-        //  Add both, NamedBody- and Body-objects, to your simulation.
+        MassiveForceHashMap forceOnBody = new MassiveForceHashMap();
+        forceOnBody.put(sun, new Vector3());
+        forceOnBody.put(earth, new Vector3());
+        forceOnBody.put(moon, new Vector3());
+        forceOnBody.put(mars, new Vector3());
+        forceOnBody.put(deimos, new Vector3());
+        forceOnBody.put(phobos, new Vector3());
+        forceOnBody.put(mercury, new Vector3());
+        forceOnBody.put(venus, new Vector3());
+        forceOnBody.put(vesta, new Vector3());
+        forceOnBody.put(pallas, new Vector3());
+        forceOnBody.put(hygiea, new Vector3());
+        forceOnBody.put(ceres, new Vector3());
+
+        for (Body b : bodies) {
+            forceOnBody.put(b, new Vector3());
+        }
+
+        long seconds = 0;
+        while (true) {
+            seconds++;
+
+            for (Massive b1 : forceOnBody.keyList()) {
+                Vector3 force = new Vector3();
+                for (Massive b2 : forceOnBody.keyList()) {
+                    if (b1 != b2) {
+                        force = force.plus(b1.gravitationalForce(b2));
+                    }
+                }
+                forceOnBody.put(b1, force);
+            }
+
+            for (Massive body : forceOnBody.keyList()) {
+                body.move(forceOnBody.get(body));
+            }
+
+            if ((seconds % 3600) == 0) {
+                cd.clear(Color.BLACK);
+                for (Massive body : forceOnBody.keyList()) {
+                    body.draw(cd);
+                }
+                cd.show();
+            }
+        }
     }
 }
diff --git a/src/SolSystem4.java b/src/SolSystem4.java
index 1f2fa19..3821347 100644
--- a/src/SolSystem4.java
+++ b/src/SolSystem4.java
@@ -12,16 +12,16 @@ public class SolSystem4 {
     public static final Body HYGIEA = new Body(8.32E19, new Vector3(-3.983943433707043E11, 2.325833000024021E11, -2.233667695713672E10), new Vector3(-6931.864585548552, -15686.8108598699, -690.5791992347208));
     public static final Body CERES = new Body(9.394E20, new Vector3(3.781372641419032E11, 1.96718960466285E11, -6.366459168068592E10), new Vector3(-8555.324226752316, 14718.33755980907, 2040.230135060142));
 
-    public static final NamedBodyForcePair SUN_NAMED = new NamedBodyForcePair("Sun", SUN);
-    public static final NamedBodyForcePair EARTH_NAMED = new NamedBodyForcePair("Earth", EARTH);
-    public static final NamedBodyForcePair MOON_NAMED = new NamedBodyForcePair("Moon", MOON);
-    public static final NamedBodyForcePair MARS_NAMED = new NamedBodyForcePair("Mars", MARS);
-    public static final NamedBodyForcePair DEIMOS_NAMED = new NamedBodyForcePair("Deimos", DEIMOS);
-    public static final NamedBodyForcePair PHOBOS_NAMED = new NamedBodyForcePair("Phobos", PHOBOS);
-    public static final NamedBodyForcePair MERCURY_NAMED = new NamedBodyForcePair("Mercury", MERCURY);
-    public static final NamedBodyForcePair VENUS_NAMED = new NamedBodyForcePair("Venus", VENUS);
-    public static final NamedBodyForcePair VESTA_NAMED = new NamedBodyForcePair("Vesta", VESTA);
-    public static final NamedBodyForcePair PALLAS_NAMED = new NamedBodyForcePair("Pallas", PALLAS);
-    public static final NamedBodyForcePair HYGIEA_NAMED = new NamedBodyForcePair("Hygiea", HYGIEA);
-    public static final NamedBodyForcePair CERES_NAMED = new NamedBodyForcePair("Ceres", CERES);
+    public static final NamedBody SUN_NAMED = new NamedBody("Sun", SUN);
+    public static final NamedBody EARTH_NAMED = new NamedBody("Earth", EARTH);
+    public static final NamedBody MOON_NAMED = new NamedBody("Moon", MOON);
+    public static final NamedBody MARS_NAMED = new NamedBody("Mars", MARS);
+    public static final NamedBody DEIMOS_NAMED = new NamedBody("Deimos", DEIMOS);
+    public static final NamedBody PHOBOS_NAMED = new NamedBody("Phobos", PHOBOS);
+    public static final NamedBody MERCURY_NAMED = new NamedBody("Mercury", MERCURY);
+    public static final NamedBody VENUS_NAMED = new NamedBody("Venus", VENUS);
+    public static final NamedBody VESTA_NAMED = new NamedBody("Vesta", VESTA);
+    public static final NamedBody PALLAS_NAMED = new NamedBody("Pallas", PALLAS);
+    public static final NamedBody HYGIEA_NAMED = new NamedBody("Hygiea", HYGIEA);
+    public static final NamedBody CERES_NAMED = new NamedBody("Ceres", CERES);
 }