В контексте конкретно сатурна могу на вики сослаться:
The propellant in just the S-IC made up about three-quarters of Saturn V's entire launch mass, and it was consumed at 13 metric tons per second (1,700,000 lb/min). Newton's second law states that force is equal to mass multiplied by acceleration, or equivalently that acceleration is equal to force divided by mass, so as the mass decreased (and the force increased somewhat), acceleration rose. Including gravity, launch acceleration was only 1 1⁄4 g, i.e., the astronauts felt 1 1⁄4 g while the rocket accelerated vertically at 1⁄4 g. As the rocket rapidly lost mass, total acceleration including gravity increased to nearly 4 g at T+135 seconds. At this point, the inboard (center) engine was shut down to prevent acceleration from increasing beyond 4 g.