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# Maths M1 Motion Question watch

1. A firework rocket starts from rest at ground level and moves vertically. In the first 3s of its motion, the rocket rises 27m. The rocket is modelled as a particle moving with constant acceleration. Find
A) the value of a
B) the speed of the rocket 3s after it has left the ground

After 3s the rocket burns out. The motion of the rocket is now modelled as that of a particle moving freely under gravity
C) find the height of the rocket above the ground 5s after it has left the ground

I have found a) as 6 and b) as 18 but i am struggling with part c
2. (Original post by Jamiemcq17)
A firework rocket starts from rest at ground level and moves vertically. In the first 3s of its motion, the rocket rises 27m. The rocket is modelled as a particle moving with constant acceleration. Find
A) the value of a
B) the speed of the rocket 3s after it has left the ground

After 3s the rocket burns out. The motion of the rocket is now modelled as that of a particle moving freely under gravity
C) find the height of the rocket above the ground 5s after it has left the ground

I have found a) as 6 and b) as 18 but i am struggling with part c
So at the height of 27m the rocket burns out and the motion is that of a particle with initial velocity 18m/s and acceleration -g m/s2 and you're looking at the displacement after 2 seconds. Add this displacement onto the 27m.
3. (Original post by RDKGames)
So at the height of 27m the rocket burns out and the motion is that of a particle with initial velocity 18m/s and acceleration -g m/s2 and you're looking at the displacement after 2 seconds. Add this displacement onto the 27m.
Ohhhh right thank you i thought the rocket fell when it burned out😂

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