How did scientists know the first astronauts' spacesuits would withstand the pressure differences in space and fully protect the astronauts inside?

Q: How did scientists know the first astronauts' spacesuits would withstand the pressure differences in space and fully protect the astronauts inside?First of all, spacesuits were not, if you'll pardon the metaphor, created in a vacuum.B.F. Goodrich made pressure suits for air

If a spacesuit weighs 280 pounds on the ground, how do astronauts manage to move around them before they enter zero gravity?

Astronauts are strapped to their sits during the take-off. They do not remove straps until they are in zero gravity. During the take-off, the thrust by the rockets is so high that they feel a pressure that restricts their motion. Just as a car suddenly accelerates to full speed

What would happen if an astronaut doesn't wear (or removes) their spacesuit? Would their body explode or would they die of suffocation?

If an astronaut is left out in space without a space suit, he would die in approximately 2.5 minutes due to lack of oxygen. He would die of the same reason why people die of drowning, hanging, CO poisioning, electric shock, and strangulation. The lack of breathable oxygen obviously prevents blood from circulating oxygen