At launch, the Space Shuttle weighs 4.5 million pounds (2.04 million kilograms). As the vehicle starts from rest on the launch pad, the booster rockets and engines accelerate it 161 km/h in just 8.0 s. What combined thrust do the booster rockets and engine exert during this period of liftoff, assuming constant acceleration? Start with a free-body diagram. If a 735 astronaut is strapped in a seat inside the shuttle, what force must this seat exert on him during liftoff? Start with a free-body diagram of the astronaut.