From ba9ca01206467088129dbf4e968ae3124f425584 Mon Sep 17 00:00:00 2001
From: "stephan.com" <stephan@stephan.com>
Date: Tue, 8 Feb 2022 17:41:28 -0800
Subject: [PATCH] 52-Kinema: ruby

---
 52_Kinema/ruby/kinema.rb | 45 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 52_Kinema/ruby/kinema.rb

diff --git a/52_Kinema/ruby/kinema.rb b/52_Kinema/ruby/kinema.rb
new file mode 100644
index 00000000..27ed2aa2
--- /dev/null
+++ b/52_Kinema/ruby/kinema.rb
@@ -0,0 +1,45 @@
+#!/usr/bin/env ruby
+
+# Kinema
+# reinterpreted from BASIC by stephan.com
+
+EPSILON = 0.15
+
+def close?(guess, answer)
+  (guess-answer).abs < answer * EPSILON
+end
+
+def ask(text, answer)
+  puts text
+  guess = gets.strip.to_f
+  if close?(guess, answer)
+    puts 'Close enough'
+    @score += 1
+  else
+    puts 'Not even close....'
+  end
+
+  puts "Correct answer is #{answer}"
+end
+
+puts 'Kinema'.center(80)
+puts 'Adapted by stephan.com'.center(80)
+puts; puts; puts;
+
+loop do
+  puts; puts
+  @score = 0
+  v = 5 + rand(35)
+
+  puts "A ball is thrown upwards at #{v} meters per second"
+
+  ask 'How high will it go? (in meters)', 0.05 * v * v
+  ask 'How long until it returns? (in seconds)', v/5.0
+
+  t = 1 + rand(2*v)/10.0
+  ask "What will its velocity be after #{t} seconds?", v - 10 * t
+  puts
+  print "#{@score} right out of 3."
+  print " not bad" if @score > 1
+  puts
+end