[填空题]
A 140-kg astronaut (including spac npc.ni54l p efi1b.) i6ez6une suit) acquires a s 0 fyse8u55u4- +b7njs3urb1qrry g qtpeed of 2.5m/s by pushing off with hist+1 5 surby- bur40ge7 n35qq8sjyf ru legs from an 1800-kg space capsule.
(a) What is the change in speed of the space capsule? m/s
(b) If the push lasts 0.40 s, what is the average force exerted on the astronaut by the space capsule? As the reference frame, use the position of the space capsule before the push. N