physics
posted by devon .
A small weather rocket weighs 15.5 N. The rocket is carried up by the balloon. The rocket is released from the balloon and fired, but its engine exerts an upward force of 11.0 N. What is the acceleration of the rocket?

thrust=ma+mg
Hmmmm. So the upward force is less than the pull of gravity, meaning a is downward.
11=15.5/9,8 a + 15.5
a= 4.5*g/15.5 downward. 
Yes if the upward force is less than gravitythen the acceleration would be downward, but it wouldn't be negative as it's not a deacceleration. :)

Devon :
a = F / m
Effective F = upward force  downward force (weight)
= 11 15.5
= 4.5 downward
a = 4.5/ (15.5/9.8)
= 2.8 m/s downwards.
(I'm pretty sure anyway)
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