## College Physics (4th Edition)

They must fire their engine for $317~seconds$
We can find the change in velocity: $\Delta v = v_f-v_0 = (1.1\times 10^4~m/s)-(2.6\times 10^4~m/s) = -1.5\times 10^4~m/s$ We can use the magnitude of the change in velocity to find the magnitude of the change in momentum: $\Delta p = m~\Delta v$ $\Delta p = (3800~kg)(1.5\times 10^4~m/s)$ $\Delta p = 5.7\times 10^7~kg~m/s$ The impulse exerted on the bird is equal to the bird's change in momentum: $F~t = \Delta p$ $t = \frac{\Delta p}{F}$ $t = \frac{5.7\times 10^7~kg~m/s}{1.8\times 10^5~N}$ $t = 317~s$ They must fire their engine for $317~seconds$.