as physics help please happy friendship day guys

[tanmaydube]

Please help me these two questions:

Q1) In a driving manual, it is suggested that, when driving at 13ms^-1(about 45 km per hour), a driver should always keep a minimum of two car-lengths between the driver's car and the one in front.
A)Suggest a scientific justification for the safety tip, making reasonable assumptions about the magnitudes of any quantities you need.
B)How would you expect the length of the 'exclusion zone' to depend on speed for speeds higher than 13ms^-1?

And the question number 2 is:

Q2) A student, standing on the platform at a railway station, notices that the first two carriages of an arriving train pass her in 2.0s, and the next two in 2.4s. The train is decelerating uniformly. Each carriage is 20 m long. When the train stops, the student is opposite the last carriage. How many carriages are there in the train?

 

[destined007]

Q1) a) justification could be that if the front cars stops suddenly, you do not crash into it. Whenever you see an obstacle, you take some time to analyse it. This is called reaction time. When you have fully analysed the situation then you apply breaks. The distance you cover after the breaks are applied is called breaking distance. The distance it will take you to stop when moving with 13ms-1 and decelerating at 15 ms-2 (lets suppose) when breaks are applied will be around 5.63 m, which is less than the length of 2 cars combined. You won't hit the front car.

b) as speed increases, length of exclusion time also increases. v^2=s/(2a)

 

[destined007]

Q2)
Tell me if i am correct.

 

[tanmaydube]

Thanks mate! You are absolutely right!

 

[hassam]

perfect soln man

 

[destined007]

You are welcome!