feat: "Ball Upwards"

Add "Ball Upwards" kata

kata/6 kyu/ball-upwards/index.test.ts

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+import maxBall from '.';
+
+describe('maxBall', () => {
+  it('should return the time of the maximum height', () => {
+    expect.assertions(4);
+
+    expect(maxBall(37)).toBe(10);
+    expect(maxBall(45)).toBe(13);
+    expect(maxBall(99)).toBe(28);
+    expect(maxBall(85)).toBe(24);
+  });
+});

kata/6 kyu/ball-upwards/index.ts

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+function maxBall(v0: number): number {
+  const g = 9.81;
+  const kmh = 3600 / 1000;
+
+  return Math.round((10 * v0) / kmh / g);
+}
+
+export default maxBall;

kata/6 kyu/ball-upwards/readme.md

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+# [Ball Upwards](https://www.codewars.com/kata/566be96bb3174e155300001b)
+
+You throw a ball vertically upwards with an initial speed `v (in km per hour)`. The height `h` of the ball at each time `t`
+is given by `h = v*t - 0.5*g*t*t` where `g` is Earth's gravity `(g ~ 9.81 m/s**2)`. A device is recording at every **tenth of second** the height of the ball.
+For example with `v = 15 km/h` the device gets something of the following form:
+`(0, 0.0), (1, 0.367...), (2, 0.637...), (3, 0.808...), (4, 0.881..) ...`
+where the first number is the time in tenth of second and the second number the height in meter.
+
+#### Task
+
+Write a function `max_ball` with parameter `v (in km per hour)` that returns the `time in tenth of second`
+of the maximum height recorded by the device.
+
+#### Examples:
+
+`max_ball(15) should return 4`
+
+`max_ball(25) should return 7`
+
+#### Notes
+
+- Remember to convert the velocity from km/h to m/s or from m/s in km/h when necessary.
+- The maximum height recorded by the device is not necessarily the maximum height reached by the ball.
+
+---
+
+## Tags
+
+- Fundamentals