# Please, can someone help me with this reaction problem

• jp0108

## Homework Statement

A ranger in a national park is driving at 47 kilometers per hour when a deer jumps onto the road 72 meters ahead the vehicle. After a reaction time of t (s), the ranger applies the brakes to produce an acceleration of -2.6 meters per second squared.

What is the maximum reaction time allowed if the ranger is to aviod hitting the deer? Answer in units of (s)

Vi = 47 km/h

d or delta x = 72

a = -2.6 m/s^2

delta t = ?

keep in mind that during the reaction period delta t, the velocity of the ranger is 47 km/h

after the delta t is passed, the velocity is reduced to 0 because of the negative acceleration -2.6

You really need to split up the question in 2 parts :

1) during the delta t
2) once the delta t is finished and the ranger is actually applying the break.
So, what formula's do you know to calculate velocity and position as a function of time ?

Also, pay attention to the given UNITS !

marlon