Momentum = (mass) x (velocity) in the direction of the velocity.
Change of momentum = "impulse" = (force) x (time)
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2-a). Momentum before the hit = (0.14) x (40) = 5.6 N-m/s toward the East.
Momentum after the hit = (0.14) x (46) = 6.44 N-m/s toward the West.
Change in momentum = (5.6) + (6.44) = 12.04 N-m/s .
(The hit soaked up all the momentum pointing east, and then provided
momentum toward the west. So the total change in momentum is the
sum of before- and after-.)
(The east momentum changed from 5.6 to zero, and the west momentum
changed from zero to 6.44. So the total change is the sum of before-and after-.)
(If you call east the positive direction, then the momentum changed
from +5.6 to -6.44, and the difference between those is 12.04 .)
2-b). 12.04 N-m/s = (Force) x (0.012 second)
Force = 12.04 / 0.012 = 1,003 and 1/3 Newtons
