Solve the all parts of given question:

Question: A 2540-kg test rocket is launched vertically from the launch pad. Its fuel (of negligible mass) provides a thrust force so that its vertical velocity as a function of time is given by v(t)=At+Bt², where A and B are constants and time is measured from the instant the fuel is ignited. At the instant of ignition, the rocket has an upward acceleration of 1.20m/s2 and 1.50s later an upward velocity of 2.05m/s.

Part A: At 3.40s after fuel ignition, what is the acceleration of the rocket?

Part B: At 3.40s after fuel ignition, what thrust force does the burning fuel exert on it, assume no air resistance? Express the thrust in Newton's.

Part C: What thrust force does the burning fuel exert on it, assume no air resistance? Express the thrust as a multiple of the rocket's weight.

Part D: What was the initial thrust due to the fuel?

I'm looking for a brief but thorough explanation, and an example.