Thrust separate from acceleration?

[bd2015]

Homework Statement

A model rocket blasts off vertically from rest at time t=0 being pushed by an engine that produces a constant thrust force F up. The engine blasts away for t seconds and then stops. Find the height y and vertical velocity that the rocket has reached by the end of the blast time t.

Homework Equations

f=ma

The Attempt at a Solution

a = F
y(t) = .5Ft^2

Is acceleration really the same as the thrust, or is acceleration the thrust - the effect of gravity?

 

[Dick]

Thrust is the force pushing the rocket up. mg is the gravitational force pulling the rocket down. Both forces are acting on the rocket while the engine is on. The 'F' in F=ma is the total force. So no, F is not the same as acceleration. You'll need to express the answer in terms of the mass 'm' of the rocket.