Dlz is very incoherent with this stuff. In the first pages of DB, kid goku lifted a car. The average car weight 1200 kg(1,2 tons). In the frieza saga, frieza threw at goku a giant massive rock, which goku easily stopped. That thing should weight at least 20 tons. That's goku in the frieza saga.
Then, in the majin buu saga, the supreme kai put 40 tons for him to lift, but he had to turn super sayan. He is a lot more powerful than when he was a kid, then when he as in the frieza saga. This scene barely made any sense, and it was most likely a pun.
People make many mistaken calculation about this. We don't know the exact proportion of PL and strenght or speed, we don't even know if there is a proportion or a pattern math relation between them. So, it's quite unsure.