# Homework Help: Constant acceleration problem involving NASA exploration vehicle.

1. Jan 11, 2009

### fuhgidabowdit

1. In Jan. 2004, NASA landed exploration vehicles on Mars. Part of the descent consisted of the following stages:?
Stage A: Friction with the atmosphere reduced the speed from 19300 km/h to 1600 km/h in 4.0 min.
Stage B: A parachute then opened to slow it down to 321 km/h in 94 s.
Stage C: Retro rockets then fired to reduce its speed to zero over a distance of 75 m.
Assume that each stage followed immediately after the preceding one and that the acceleration during each stage was constant.

1.Find the rocket's acceleration (in m/s^2 ) during stage C.

2.What total distance (in m} did the rocket travel during stage A?

3.What total distance (in km) did the rocket travel during stage C?

V1= V0 + a1T
x-x0= V0T + 1/2a1T6
(V1)^2- (V0)^2 = 2a1(T^2)(x-x0)
a1= acceleration T=time Vo=initial velocity x,x0= position, initial position

The last question isnt that just 75 m converted to KM? I put that in and I got the answer wrong. Also for #1 I got -0.05 and I got that wrong too. And for #2 I got 356m and got that wrong too. I used the above equations to get all of these answers. What am i doing wrong? Please Help. Thanks

2. Jan 11, 2009

### alphysicist

Hi fuhgidabowdit,

Looking at #1, how did you get -0.05 (and what numbers did you use to get it)?

3. Jan 11, 2009

### fuhgidabowdit

hey thanks for replying. I figured out what I was doing wrong. It was just some stupid algebraic mistakes.