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.
Newton has 3 Laws specifically The Three Laws of Motion
Answer:
a) T=1.35s
b) amplitude = 0.0923m
Explanation:
m=300 gr
k=6.5 N/m
first we need to get the angular frequency of the motion
so we have that
ω = √(k/m)
in this case motion is a simple harmonic so the period is defined by:
T= 2π / ω
T= 2π / √(k/m)
replacing the variables...
T= 2π / √(6.5/0.3)
T=1.35s (period of the block's motion)
and...
α max = | ω²r max |
2 = (2π/1.35)² * r max
r max= 0.0923m
Here is the full question:
The rotational inertia I of any given body of mass M about any given axis is equal to the rotational inertia of an equivalent hoop about that axis, if the hoop has the same mass M and a radius k given by:

The radius k of the equivalent hoop is called the radius of gyration of the given body. Using this formula, find the radius of gyration of (a) a cylinder of radius 1.20 m, (b) a thin spherical shell of radius 1.20 m, and (c) a solid sphere of radius 1.20 m, all rotating about their central axes.
Answer:
a) 0.85 m
b) 0.98 m
c) 0.76 m
Explanation:
Given that: the radius of gyration
So, moment of rotational inertia (I) of a cylinder about it axis = 





k = 0.8455 m
k ≅ 0.85 m
For the spherical shell of radius
(I) = 




k = 0.9797 m
k ≅ 0.98 m
For the solid sphere of radius
(I) = 




k = 0.7560
k ≅ 0.76 m