Can I get some physics help?

Block 1, of mass m1 = 1.50 kg , moves along a frictionless air track with speed v1 = 27.0 m/s . It collides with block 2, of mass m2 = 31.0 kg , which was initially at rest. The blocks stick together after the collision. Find the magnitude pi of the total initial momentum of the two-block system.Find vf, the magnitude of the final velocity of the two-block system. What is the change ΔK=Kfinal−Kinitial in the two-block system's kinetic energy due to the collision? - not gonna lie, I don't know where to go at all

A 129-kg astronaut (including space suit) acquires a speed of 2.40 m/s by pushing off with her legs from a 1850-kg space capsule. Use the reference frame in which the capsule is at rest before the push. What is the velocity of the space capsule after the push in the reference frame? If the push lasts 0.680 s , what is the magnitude of the average force exerted by each on the other? What is the kinetic energy of the astronaut after the push in the reference frame? What is the kinetic energy of the capsule after the push in the reference frame? - I have no idea how to do this one either :(