May someone me fast this is ! 1

1.) what is an input force?

a.) the force a person applies to a simple machine

b.) the net force on a system

c.) the force a simple machine applies to an object

d.) the applied force on a system

the only real purpose of sputnik 1 was to beat the us into space. we were getting close to launching a useful satellite, explorer 1 - which launched on january 31, 1958. the ussr had to beat that, so they launched sputnik 1 on october 4, 19

you can cut your hand off if your not