Final answer:
The force exerted by the astronaut on their chair when accelerating straight up can be calculated using Newton's second law.
Step-by-step explanation:
When an astronaut is accelerating straight up, they exert a force on their chair. The amount of force can be calculated using Newton's second law, which states that force equals mass times acceleration (F = ma). In this case, the force exerted by the astronaut on the chair would be equal to the astronaut's mass multiplied by their acceleration.
For example, if the astronaut has a mass of 70 kg and is accelerating at 12 m/s², the force exerted on the chair would be:
F = 70 kg x 12 m/s² = 840 N