- #1

DracoMalfoy

- 88

- 4

## Homework Statement

A Rocket with an engine that causes a

__launches with an__

**net acceleration of 4m/s^2****The engine**

__initial velocity of 20m/s__.__fuel lasts for__

**0.8s****.**A secondary engine then fires causing a

**How far off the ground is the rocket when the secondary rocket runs out of fuel?**

__net acceleration of 2m/s^2 for 0.6s__## Homework Equations

- Vf=Vi+a⋅t
- Δd=Vi⋅t+2a⋅Δd

- Δd=1/2(Vf+Vi)t

**(Vf: Final Velocity, a= Acceleration, t= Time, Δd= Displacement)**

## The Attempt at a Solution

1. First I drew a picture of what this would look like including the data.

2. I listed the data.

Given:

__Engine 1(Points A-B)__[/B]

a: 4m/s^2

Vi: 20m/s

t: 0.8s

__Engine 2(Points B-C)__a:2m/s^2

t: 0.6s

**3. I'm assuming that each engine has their own separate equation. I'm thinking that displacement is what needs to be found for each engine at their own points and then added to find the total?**

4. For engine 1 I thought that the equation for the final velocity should be used since I guess that is needed for the second engines initial velocity.

4. For engine 1 I thought that the equation for the final velocity should be used since I guess that is needed for the second engines initial velocity.

Vf=Vi+a⋅t

I substituted values and got

**23.2m**as the final velocity

~Im not sure what to do next or even if that was the correct step to first take.