Contents

require 'minitest/autorun'
require 'driving_physics/scalar_force'

include DrivingPhysics

describe ScalarForce do
  # i.e. multiply this number times speed^2 to approximate drag force
  it "calculates a reasonable drag constant" do
    expect(ScalarForce.air_resistance 1).must_be_within_epsilon DRAG
  end

  # ROT_COF's value is from observing that rotational resistance
  # matches air resistance at roughly 30 m/s in street cars
  it "approximates a reasonable rotational resistance constant" do
    expect(30 * ScalarForce.air_resistance(1)).must_be_within_epsilon ROT_COF
  end

  it "approximates a positive drag force" do
    expect(ScalarForce.air_resistance 30).must_be_within_epsilon 383.13
  end

  it "approximates a positive rotational resistance force" do
    expect(ScalarForce.rotational_resistance 30).must_be_within_epsilon 383.13
  end

  it "approximates a positive rolling resistance force" do
    nf = 1000 * G
    expect(ScalarForce.rolling_resistance nf).must_be_within_epsilon 98.0
  end
end

Version data entries

3 entries across 3 versions & 1 rubygems

Version	Path
driving_physics-0.0.1.1	test/scalar_force.rb
driving_physics-0.0.0.3	test/scalar_force.rb
driving_physics-0.0.0.2	test/scalar_force.rb