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Water from a fire hose is directed horizontally against a wall at a rate of $50\mathrm{.}0$ kg$/$s and a speed of $42\mathrm{.}0$ m$/$s$.$ Calculate the magnitude of the force exerted on the wall, assuming the water$$s horizontal momentum is reduced to zero.

A runaway train car that has a mass of $15,000$ kg travels at a speed of $5\mathrm{.}4$ m$/$s$5\mathrm{.}4$ m$/$s down a track. Compute the time required for a force of $1500$ N to bring the car to rest.