update description project motion

subjects/project_motion/README.md

@@ -2,16 +2,27 @@
 
 ### Instructions
 
-For this exercise you will have to create a [projectile motion](https://cimg2.ck12.org/datastreams/f-d%3Abb024be6673110b31e78b46819e792adaed8dc661e082a61f0a6d64e%2BIMAGE%2BIMAGE.1).
+For this exercise, you will have to create a [projectile motion](https://cimg2.ck12.org/datastreams/f-d%3Abb024be6673110b31e78b46819e792adaed8dc661e082a61f0a6d64e%2BIMAGE%2BIMAGE.1).
 
-A structure called `Object` will be provided which will have all variables that are
-essential for the projectile physics. (distance, velocity, height, time)
+Two structures will be provided. A structure called `ThrowObject` that will contain all the variables that are
+essential for the projectile physics (initial position, initial velocity, current position, current velocity and time).
+
+A structure called `Object` which will have the corresponding values of X and Y of the initial position, the initial velocity, the current position and the current velocity. 
 
 You must implement :
 
-- A function `throw_object` that will initialize the Object with a given velocity and height.
-- The trait Iterator with the `.next()` in which,the next position of the object after 1 second, must be calculated.
-  It will return an `Option` with the Object or it will return `None` if the object already reached the floor.
+- A function `new` that will initialize the ThrowObject with a given initial position and an initial velocity.
+- The trait Iterator with the `.next()` in which the position and speed of the object must be calculated after 1 second.
+  It will return an `Option` with the ThrowObject, or it will return `None` if the ThrowObject has already reached the floor.
+
+Consider the value of gravity is 9.8m/(s*s) and that the position (p) in the instant s of an object is given by:
+
+$$ p(t) =  p_{0} + v_{0}*t +\frac{1}{2}* a*t^{2} $$
+
+and velocity (v) in the instant s of an object is given by:
+
+$$ v(t) =  v_{0} + a*t $$
+
 
 ### Notions
 
@@ -24,17 +35,25 @@ You must implement :
 
 #[derive(Debug, Clone, PartialEq)]
 pub struct Object {
-    pub distance: f32,
-    pub velocity: f32,
-    pub height: f32,
+    pub x: f32,
+    pub y: f32,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct ThrowObject {
+    pub init_position: Object,
+    pub init_velocity: Object,
+    pub actual_position: Object,
+    pub actual_velocity: Object,
     pub time: f32,
 }
 
-impl Object {
-    pub fn throw_object(velocity: f32, height: f32) -> Object {}
+impl ThrowObject {
+    pub fn new(init_position: Object, init_velocity: Object) -> ThrowObject {
+    }
 }
 
-impl Iterator for Object {
+impl Iterator for ThrowObject {
   // next
 }
 
@@ -48,8 +67,7 @@ Here is a program to test your function
 use project_motion::*;
 
 fn main() {
-    let mut obj = Object::throw_object(50.0, 150.0);
-    println!("{:?}", obj.next());
+    let mut obj = ThrowObject::new(Object { x: 50.0, y: 50.0 }, Object { x: 0.0, y: 0.0 });
     println!("{:?}", obj.next());
     println!("{:?}", obj.next());
     println!("{:?}", obj.next());
@@ -62,10 +80,9 @@ And its output:
 
 ```console
 $ cargo run
-Some(Object { distance: 50.0, velocity: 50.0, height: 145.1, time: 1.0 })
-Some(Object { distance: 100.0, velocity: 50.0, height: 125.5, time: 2.0 })
-Some(Object { distance: 150.0, velocity: 50.0, height: 81.4, time: 3.0 })
-Some(Object { distance: 200.0, velocity: 50.0, height: 3.0, time: 4.0 })
+Some(ThrowObject { init_position: Object { x: 50.0, y: 50.0 }, init_velocity: Object { x: 0.0, y: 0.0 }, actual_position: Object { x: 50.0, y: 45.1 }, actual_velocity: Object { x: 0.0, y: -9.8 }, time: 1.0 })
+Some(ThrowObject { init_position: Object { x: 50.0, y: 50.0 }, init_velocity: Object { x: 0.0, y: 0.0 }, actual_position: Object { x: 50.0, y: 30.4 }, actual_velocity: Object { x: 0.0, y: -19.6 }, time: 2.0 })
+Some(ThrowObject { init_position: Object { x: 50.0, y: 50.0 }, init_velocity: Object { x: 0.0, y: 0.0 }, actual_position: Object { x: 50.0, y: 5.9 }, actual_velocity: Object { x: 0.0, y: -29.4 }, time: 3.0 })
 None
 None
 $