A rocket, weighing 4.36 x 10^4 N, has an engine that provides an upward force of 8.90 x 10^5 N. It reaches a maximum speed of 860 m/s. How long must the engine burn in order to reach this speed?
I know that the net force is 846,400 N and that the time is equal to the change in momentum times velocity over that numerical value. But I am not sure how to solve it. Any help is appreciated, and thank you in advance.
2007-01-21 17:37:58 · 1 answers · asked by A.R 2 in Science & Mathematics ➔ Physics
The original momentum is 0. The final momentum is 860 m/s multiplied by the mass. You need to find the mass first; we can derive it from the weight. Using g = 9.81 m/s^2 we get m = 4.36 * 10^4 / 9.81 = 4.44 * 10^3 kg. So the change in momentum is 860(4.44*10^3) = 3.82 * 10^6 kg m/s.
Then F = Δp / t
=> 8.46 * 10^5 = 3.82 * 10^6 / t
=> t = 4.52 seconds.
2007-01-21 17:47:33 · answer #1 · answered by Scarlet Manuka 7 · 0⤊ 0⤋