I have a class member
I created a rigid body they same way it is done in the HelloWorld demo, along with a btDiscreteDynamicsWorld* dynamicsWorld from the demo also.
Later I use carBody->applyImpulse(btVector3(0.f,0.5f, 0.f), btVector3(0.f, 0.f, 0.f)).
If I call applyImpulse early, then the impulse is applied and the block takes off. If I wait some time to use it, then nothing happens and the block stays stationary. I am more than willing to post code, or create a test case, but I have not done so yet, maybe there is something obvious I am missing.