The kinetic energy of any object is . . . . . (1/2) · (mass) · (speed²) .
For this object . . . . . 18J = (1/2) · (4 kg) · (speed²)
Divide each side by 2 kg . . . . . 9 m²/s² = speed²
Square root each side . . . . . 3 m/s = speed
We can't calculate the velocity because we don't know anything about the direction the object is moving.
