A 10 metric ton train moves toward the south at 40 m/s. At what speed must it travel to have four times its original momentum?

Answer 1

momentum = mv = (10,000 kg)(40 m/s) = 400,000 kgm/s

4 times momentum is 4 x 400,000 = 1,600,000 kgm/s

so 10,000v = 1,600,000

v = 160 m/s