Answer: F = 1235 N
Explanation: Newton's Second Law of Motion describes the effect of mass and net force upon acceleration:
Acceleration is the change of velocity in a period of time:
Velocity of the car is in km/h. Transforming it in m/s:
v = 13 m/s
At the moment the car decelerates, acceleration is
a = 65 m/s²
Then, force will be
= 1235 N
The horizontal net force the straps of the restraint chair exerted on the child to hold her is 1235 newtons.