[填空题]
A 140-kg astronaut (including space suityosg4xg( jw- n) fvv3,) acquires a speed of 2.5m/0exap.dk.*;jmj .9 d ddjr7afs by pushing offpadad .x*7 j.9 jfr0;.mkde jd with his 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