Answer:
b) d = 0.71 Km
Explanation:
Car kinematics
Car 1 moves with uniformly accelerated movement
[tex]v_f^2=v_o^2+2a*d[/tex] Formula (1)
d: displacement in meters (m)
v₀: initial speed in m/s
vf: final speed in m/s
a: acceleration in m/s²
Equivalences:
1mile = 1609.34 meters
1 hour = 3600s
1km = 1000m
Known data
[tex]v_o = 69\frac{mile}{hour} *1609.34\frac{meter}{mile} *\frac{1}{3600}\frac{hour}{s}=30.8 \frac{m}{s}[/tex]
[tex]v_f= \frac{69}{2} \frac{mile}{hour} =34.5\frac{mile}{hour}=15.4 \frac{m}{s}[/tex]
a = -0.5 m/s²
Distance calculation
We replace data in the Formula (1)
[tex]15.4^2 = 30.8^2+2(-0.5)*d[/tex]
[tex]2(0.5)*d = 30.8^2 - 15.4^2[/tex]
[tex]d =\frac{ 30.8^2 - 15.4^2}{2(0.5) }= 717.6m[/tex]
[tex]d = 717.6 m\frac{1km}{1000m} = 0.7176Km[/tex]
