How to access specific value from model choice field in django

So i have this material models which contain 3 values and can be selected from dropdown menu in the template, how can access this exact "tegangan_tarik" and "tegangan_values to be included in my output page

models.py

class Materials(models.Model):
    SAE_Number = models.CharField(max_length=64)
    tegangan_tarik = models.FloatField()
    tegangan_luluh = models.FloatField()

    def __str__(self):
        return f"{self.SAE_Number}: Su = {self.tegangan_tarik} MPa; Sy = {self.tegangan_luluh} MPa"

forms.py

from django import forms
from .models import *


class MyForm(forms.Form):
    N = forms.FloatField(label="Faktor Keamanan ",
                            widget=forms.NumberInput(attrs={'value': '2.0', 'min': '0'}))
    T = forms.FloatField(label="Momen Puntir / Torsi ",
                            widget=forms.NumberInput(attrs={'placeholder': 'N-mm', 'min': '0'}))
    Material = forms.ModelChoiceField(
                            label = "Pilih Bahan :", queryset = Materials.objects.all())
    Ft = forms.FloatField(label="Gaya Tangensial Pada Elemen (Ft) ",
                            widget=forms.NumberInput(attrs={'placeholder': 'N', 'min': '0'}))
    Fr = forms.FloatField(label="Gaya Radial Pada Elemen (Fr) ",
                            widget=forms.NumberInput(attrs={'placeholder': 'N', 'min': '0'}))
    AB = forms.FloatField(label="Jarak Antara Bantalan A ke Elemen B (AB) ",
                            widget=forms.NumberInput(attrs={'placeholder': 'mm', 'min': '0'}))
    BC = forms.FloatField(label="Jarak Antara Bantalan C ke Elemen B (BC) ",
                            widget=forms.NumberInput(attrs={'placeholder': 'mm', 'min': '0'}))

views.py

from django.shortcuts import render
from .forms import *


import math
 

# Create your views here.
def input(request):
    return render(request, "shaft/input.html", {
        "form": MyForm(),
    })

def output(request):

    N = float(request.POST['N'])
    T = float(request.POST['T']) 
    Sy = #how to access this tegangan_tarik value from the models
    Su = #how to access this tegangan_luluh value from the models
    Ft = float(request.POST['Ft']) 
    Fr = float(request.POST['Fr']) 
    AB = float(request.POST['AB']) 
    BC = float(request.POST['BC']) 

    # Menghitung Gaya Reaksi Tumpuan
    Az = (Ft * BC) / (AB + BC)
    ...
    ...

input.html

{% extends "shaft/layout.html" %}
{% load static %}

        {% block title %}Input Form{% endblock %}

{% block body %}
    <h1>INPUT PAGE</h1>
    <form action="{% url 'shaft:output' %}" method="post">
        {% csrf_token %}
         {{ form.as_p }}
            <input type="submit">
    </form>

</body>
{% endblock %}

I dont really know what to do 🙁