The answer is it is between being eaten by a hyena and a crocodile. To get this result, first paleontologists uncovered a fossil with bite marks that are thought to be from a young T. rex specimen. The spacing and dimensions of punctures on the fossilized vertebrae of an edmontosaurus, a type of duck-billed dinosaur, were compared to various T. rex fossils of different ages and found to match those between 11-12 years old.
After identifying that it was from the T. rex, scientists attempted to duplicate the depth and shape of the wounds today. Researchers mounted a tooth made of dental-grade cobalt-chromium alloy on an “electromechanical testing system”, a biting machine, then “bit” a cow bone. After examining the wounds on the cow bone for similarity to the edmontosaurus they found that the young T. rex must have had significant bite force up to 5,600 N compared to the measly bite force of 300 N in humans. Adult or fully grown the T. rex had bite forces of up to 35,000 N, enough to pulverize bones as seen in the coprolites of T. rex. Potentially enough to crush a car.