Other source:
Gohan suddenly senses an energy signal from the village that Vegeta destroyed earlier, and goes to check it out. Krillin arrives back at the cave to give Bulma the good news, however, Zarbon and Vegeta followed him. They see that he has a Dragon Ball, and they decide to fight each other for it. Zarbon thinks that the fight will be as easy as it was the last time, but he doesn't know that a Saiyan's strength increases after he recovers from injury, and Vegeta makes short work of him. He then takes Krillin's Dragon Ball back to where he hid the other five. Meanwhile, Goku's ship hits a magnetic storm, which makes the gravity machine malfunction, causing it to increase the gravity to 100x normal. Though he can barely move, Goku sees this as a new challenge, and begins to train under the intense gravity.
