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.
A)
Let's start by writing the equation of the forces along the directions parallel and perpendicular to the incline:
Parallel:
(1)
where
m is the mass
g = 9.8 m/s^2 the acceleration of gravity
is the coefficient of friction
R is the normal reaction
a is the acceleration
Perpendicular:
(2)
From (2) we find
And substituting into (1)
Solving for a,
B) 5.94 m/s
We can solve this part by using the suvat equation
where
v is the final velocity
u is the initial velocity
a is the acceleration
s is the displacement
Here we have
v = ?
u = 0 (it starts from rest)
s = 8.70 m
Solving for v,