# Thread: Acceleration of a rocket ..

1. ## Acceleration of a rocket ..

A rocket is launched straight up with a constant acceleration of 200 feet per sec each sec.

A. Find the rocket's velocity 20 sec after launch
B. Find its altitude at the end of 20 sec
The results are a. 550 ft per sec b. 40,550 ft high
I am just having problems showing the steps !!!

2. Originally Posted by xterminal01
A rocket is launched straight up with a constant acceleration of 200 feet per sec each sec.

A. Find the rocket's velocity 20 sec after launch
B. Find its altitude at the end of 20 sec
The results are a. 550 ft per sec b. 40,550 ft high
I am just having problems showing the steps !!!
Where'd you get those results?

3. Originally Posted by xterminal01
A rocket is launched straight up with a constant acceleration of 200 feet per sec each sec.

A. Find the rocket's velocity 20 sec after launch
B. Find its altitude at the end of 20 sec
The results are a. 550 ft per sec b. 40,550 ft high
I am just having problems showing the steps !!!

a)

$v = v_0 + at$

a rocket starts from rest, $v_0 = 0$

$v = 200(20) = 4000$ ft/s

b) $d = v_0 t + \frac{1}{2}at^2$

$d = \frac{1}{2}(200)(20^2) = 40000$ ft

4. Originally Posted by xterminal01
A rocket is launched straight up with a constant acceleration of 200 feet per sec each sec.

A. Find the rocket's velocity 20 sec after launch
B. Find its altitude at the end of 20 sec
The results are a. 550 ft per sec b. 40,550 ft high
I am just having problems showing the steps !!!
$\int{200}dt=200t+c=V(t)$

at t=0, v(t)=0, therefore c=0

$\int{200t}=100t^2+c=s(t)$

again, at t=0, s(t)=0, therefore c=0

Altitude= $s(20)=100(20)^2=40,000$