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astenroo
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Homework Statement
A polaris missile has a mass of 1.4 x 10^4 kg and its engine has a thrust of 2 x 10^5 N. If its engines fire in the vertical direction for 1 min starting from rest, to what vertical height would it rise in the absence of air resistance?
Homework Equations
F=ma
W=mg
y=.5at^2
The Attempt at a Solution
So, I figured F-W=ma, where a is the upward acceleration, F is the thrust, W is the wight of the rocket and m is the mass of the rocket. This would produce a total upward acceleration of a= (F-W)/m=4.49 m/s^2. The distance y is then y=0.5 x 4,49 x 60^2=8074 m. The correct answer should be 11.8 km (3.7 km in free fall).
Where am I thinking wrong here?