Final answer:
Olaf has more momentum when he is chasing his head (scenario B) with a mass of 13 kg and velocity of 19 m/s, resulting in a momentum of 247 kg·m/s, compared to when he is skating with his entire body with a momentum of 240 kg·m/s.
Step-by-step explanation:
To determine when Olaf has more momentum, we must consider the definition of momentum in physics, which is the product of an object's mass and velocity (p = mv). In scenario A, Olaf's momentum can be calculated by multiplying his mass (20 kg) by his velocity (12 m/s), resulting in a momentum of 240 kg·m/s. In scenario B, despite the increase in speed by 7 m/s (making his velocity 19 m/s), Olaf's mass is reduced to 13 kg, resulting in a momentum of 247 kg·m/s. Therefore, Olaf has more momentum in scenario B when he is chasing his head, even though his mass is less.