1. Understand the Formula

The kinetic energy (KE) of an object is given by the following formula:

KE = (1/2) * m * v²

where:

* KE is the kinetic energy (in Joules)

* m is the mass (in kilograms)

* v is the velocity (in meters per second)

2. Rearrange the Formula to Solve for Mass

We need to solve for mass (m), so let's rearrange the formula:

m = (2 * KE) / v²

3. Plug in the Values

Now, plug in the given values:

* KE = 18 J

* v = 3.0 m/s

m = (2 * 18 J) / (3.0 m/s)²

4. Calculate the Mass

m = 36 J / 9 m²/s²

m = 4 kg

Answer: The mass of the rolling ball is 4 kg.