Vo = 110km/h = 110000m/3600s = 30.56 m/s
V^2 = Vo^2 + 2a*d = 0
a = -(Vo^2)/2d = -(30.56^2)/200 = -4.67
m/s^2.
F = m*a = 3.6*10^5 * (-4.67) = -1.68*10^6 N.
Note: The negative sign means that the force opposes the motion.
Superman must stop a 110-km/h train in 100m to keep it from hitting a stalled car on the tracks. The train's mass is 3.6 × 105 kg.
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