A soccer ball has a kinetic energy of 20 joules when it travels at a speed of 36 km / h. Determine the mass of the ball.

Given:

v = 36 kilometers per hour – soccer ball speed;

W = 20 Joules – the kinetic energy of a soccer ball.

It is required to determine m (kilogram) – the mass of the soccer ball.

Let’s convert units of speed to meters per second:

v = 36 kilometers per hour = 36 * 10/36 = 10 meters per second.

Then the mass of the ball will be equal to:

m = 2 * W / v ^ 2 = 2 * 20/10 ^ 2 = 40/100 = 0.4 kilograms.

Answer: The mass of a soccer ball is 0.4 kilograms (400 grams).