An astronaut is piloting her spacecraft

[donchinkjao]

Homework Statement

An astronaut is piloting her spacecraft towards the International Space station. To stop the spacecraft, she fires the retro-rockets, which cause the spacecraft to slow down from 20.0m/s [E] to 0,0 m/s in 12 s.

Relevant Equations

vf=vi+at

Find acceleration

vi=20.0 m/s[E]
vf= 0
t= 12 s
a= ?

0 =20+ a(12)
0-20 = a(12)
-20/12=a

-1.7m/s2 [E]= a

textbook says it's 1.7m/s [W]
Is it because when velocity decreases, it increases west (opposite direction)? Is -1.7m [E] same as 1.7m [W]??

 

[Drakkith]

Is it because when velocity decreases, it increases west (opposite direction)? Is -1.7m [E] same as 1.7m [W]??

That's right.