Answer:
0.51
Explanation:
m = Mass = 70 kg
g = Acceleration due to gravity = 9.81 m/s²
t = Time taken
u = Initial velocity = 80 km/h = 80/3.6 = 22.22 m/s
v = Final velocity
a = Acceleration
s = Displacement = 50 m
[tex]v^2-u^2=2as\\\Rightarrow a=\frac{v^2-u^2}{2s}\\\Rightarrow a=\frac{0^2-22.22^2}{2\times 50}\\\Rightarrow a=-4.93\ m/s^2[/tex]
[tex]F=ma\\\Rightarrow F=70\times 4.93\\\Rightarrow F=345.1[/tex]
[tex]F=\mu N\\\Rightarrow 345.1=\mu \times 70\times 9.81\\\Rightarrow \mu=\frac{345.1}{70\times 9.81}\\\Rightarrow \mu=0.51[/tex]
Kinetic coefficient of friction between the road and the crate is 0.51
