Final answer:
The force exerted by an 89 kg astronaut on his chair while sitting at rest on the launch pad is approximately 872.2 N.
Step-by-step explanation:
An astronaut at rest on the launch pad exerts a normal force on his chair, which is equal in magnitude and opposite in direction to the force exerted by the chair on the astronaut. This normal force is equal to the product of the astronaut's mass and the acceleration due to gravity.
Using the formula F = mg, where m is the mass of the astronaut and g is the acceleration due to gravity (approximately 9.8 m/s²), we can calculate the force:
F = (89 kg)(9.8 m/s²) = 872.2 N
Therefore, the astronaut exerts a force of approximately 872.2 N on his chair while sitting at rest on the launch pad.