Converting 30km/hr into m/s
u=25/3 m/s
v=0
We will use the expression v2−u2=2aS
a) With the seat belt S=30 cm =0.3 m
v2−u2=2aS−9625=2×a×0.3a=−5.4625ms−2=−115.75ms−2
Force = ma = 70×115.75=8.1kN
b) Without the seat belt S=5 cm = 0.05 m
v2−u2=2aS−9625=2×a×0.05a=−0.9625ms−2=−694.4ms−2
Force = ma = 70×694.4=48.61kN
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