Answer:
a) 0.067 seconds
b) 112.5 m/s²
Explanation:
t = Time taken
u = Initial velocity = 7.5 m/s
v = Final velocity = 0
s = Displacement = 0.25 m
a = Acceleration
Eqaution of motion
[tex]v^2-u^2=2as\\\Rightarrow a=\frac{v^2-u^2}{2s}\\\Rightarrow a=\frac{0^2-7.5^2}{2\times 0.25}\\\Rightarrow a=-112.5\ m/s^2[/tex]
b) The deceleration of the football player is 112.5 m/s²
[tex]v=u+at\\\Rightarrow t=\frac{v-u}{a}\\\Rightarrow t=\frac{0-7.5}{-112.5}\\\Rightarrow t=0.067\ s[/tex]
a) The collision lasts for 0.067 seconds
