A Rocket engine?

Question

A rocket engine can accelerate a rocket launched from rest vertically up with an acceleration of 20.0 m/s^2. however after 50.0s of flight the engine fails. g= 9.80 n/kg

what is the rockets' altitude when the engine fails?
when does it reach its maximum height?
what is the maximum height reached?
what is the velocity of the rocket just before it hits the ground?


What are the formulas' that I use to find these answers?

The reason I asked is because I dont't understand what to do? If I could understand the book then I would use it...

Answer 1

(i)s=ut+0.5at^2 =0.5(20)(50)^2=25000 m
Altitude when engine fails is 25 000 m.
(ii)v=u+at =20(50)=1000 m/s
Speed when engine fails is 1000 m/s.
0=1000-9.8t
t=102 s
Time for rocket to reach maximum height=50+102=152 s
(iii) v^2=u^2+2as
0=1000^2-2(9.8)s
s=51020 m
Maximum height=25000+51020=76020 m
(iv) v^2=u^2+2as
=2(9.8)(76020)=1489992
v=1220.7
Velocity when it reach ground=1220.7 m/s.

Answer 2

Hey, this looks like your class assignment. Nevertheless, you can refer back to books, man.

Answer 3

ask ur teacher