# Homework Help: Displacement Problems

1. Aug 24, 2009

### cyspope

1. The problem statement, all variables and given/known data
A rocket starts from rest and accelerates for 3.50 s with an acceleration of 5.00 m/s². If it continues to rise until its velocity is zero, what will be its maximum height?

2. Relevant equations
I thought I had to use the "UNIFORM MOTION with CONSTANT ACCELERATION" formula, which is d=vi*t+(1/2)*a*t²
d = distance
vi = initial velocity
t = time
a = acceleration

3. The attempt at a solution
d = 0*3.5+(1/2)(5.00 m/s²)(3.5)²

I am not sure whether I set up the problem correctly or not.

2. Aug 24, 2009

### drizzle

hey cyspope,
what's the velocity of the rocket after 3.50 s? use this velocity* to determine the extra displacement, [this will be the initial velocity vo], you may use the velocity & displacement equation.

* note the rocket will be decelerating under the effect of g = 9.8 m/s2 till the velocity reaches zero.

3. Aug 24, 2009

### cyspope

It doesn't says about the velocity of the rocket after 3.50 s. and How would you apply the gravity, which is 9.8 m/s² into the equation?

4. Aug 24, 2009

### drizzle

hint:

5. Aug 24, 2009

### drizzle

don't forget, there're two different displacements, d1 [which you can calculate using the first part of the question], and d2 [as described above]. the maximum displacement [height] is then d1+d2

6. Aug 2, 2011