In space there is nothing for the rocket to push against so how ...

[DelorasTo]

In space there is nothing for the rocket to push against so how does it accelerate?
 
  What will be an ideal response?

Question 2

A ball is thrown straight up with a speed of 30 m/s. (a.) How long does it take the ball to reach the maximum height? (b.) What is the maximum height reached by the ball? (c.) What is its speed after 4.2 s?
 
  What will be an ideal response?

[chevyboi1976]

Answer to Question 1

In terms of forces, the rocket pushes the exhaust gases back and they in turn (action-reaction) push the rocket forward. In terms of momentum, in order to conserve momentum since the exhaust gases acquire negative momentum (moving backwards) the rocket acquires positive momentum (increasing velocity forward).

Answer to Question 2

(a.) 3.1 s
(b.) 46 m
(c.) 11 m/s