Answer:
n=15
Explanation:
First of all let's define all the variables,
The total number of cars is given by n
The initial speed of the three cars is v
The final speed of all cars is [tex]\frac {v} {5}[/tex]
The mass of each car is m
So applying the conservation of the moment, we have
[tex]3mv + mv_1 + mv_2 .... = n (m) \frac {v} {5}[/tex]
as [tex]v_2 = v_3 = v_4 ... = 0m / s[/tex],
We have to,
[tex]3mv = n (m) \frac {v} {5}[/tex]
n = 15
The total number of cars is 15