Weather rocket constant acceleration and speed at altitude

[BOTG]

Lost please help!

A 1974 kg weather rocket is launched straight up. The rocket motor provides a constant acceleration for 20.27 s, then the motor stops. The rocket altitude 23.94 s after launch is 7242. You can ignore any effects of air resistance.

What was the rocket's acceleration during the first 20.27 s?
What is the rocket's speed as it passes through a cloud 7242 m above the ground?

 

[Dick]

The rocket is under a constant acceleration (call it 'a') during the first part of the trip (the first 20.27 secs), and under a constant acceleration of -g thereafter. You just have to splice these two solutions together. What equations do you know that govern motion under constant acceleration?