(I apologize in advance if this should have been merged with my other topic.(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

A 1000kg weather rocket is launched straight up. The rocket motor provides a constant acceleration for 16s, then the motor stops. The rocket altitude 20s after launch is 5100m. You can ignore any effects of air resistance.

A) What was the rocket's acceleration during the first 16s?

B) What is the rocket's speed as it passes through a cloud 5100m above the ground?

2. Relevant equations

d = vi(t) + (1/2)(a)(t^{2})

3. The attempt at a solution

5100 = d_{total}

d_{first}= 0 + (1/2)(a)(16^{2})

d_{second}= v_{0}- (1/2)(9.8)(16)

v0 = 16a

So the combining the equations:

d_{total}= d_{first}+ d_{second}

5100 = 0 + (1/2)(a)(16^{2}) + v_{0}- (1/2)(9.8)(16)

5100 = 128a + 16a - 78.4

5178.4 = 144a

a = 35.96

Now, our homework is checked automatically, so I'm not sure if I'm rounding incorrectly or what, but any help would be appreciated.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Free Fall of a rocket

**Physics Forums | Science Articles, Homework Help, Discussion**