A rocket sled of total mass 2100 kg has an initial acceleration of 49 m/s^2 while friction opposing the motion is 650 N. Four identical rockets drive it. What thrust does each rocket produce?

1. The vertical forces cancel, so only the horizontal forces matter. 2. The four thrusts add while friction opposes them, so the net force is four times the thrust minus the friction. 3. Newton's second law sets that net force equal to the mass times the acceleration. 4. Rearranged, four times the thrust equals the mass times the acceleration plus the friction. 5. Substitute the values: (2100 kg)(49 m/s^2) + 650 N = 102900 N + 650 N. 6. That total is 1.0 x 10^5 N for all four rockets together. 7. Divide by four to get the thrust of a single rocket: 2.6 x 10^4 N. 8. Quoting 1.0 x 10^5 N reports the combined thrust rather than the thrust of one rocket. _Source: OpenStax College Physics (CC BY 4.0), Ch 4 "Dynamics: Force and Newton's Laws of Motion", section 4.3 Newton's Second Law of Motion: Concept of a System_