How do you work out the reaction distance?

[littlemissbee]

how do you work out the reaction distance??

i have this big assignment to do at school and i can't work out how to find the breaking and reaction distances ... i have a Vi = 0 Vf= 69km/h reaction time= 0.78sec deceleration of 4.49m/s and my total distance i need to find if i go over is 41 m ... i was thinking of useig d=(1/2 (Vf+Vi)xT for my reaction and i don't know how to do the breaking ?? :/ can anyone give me any sujestions on how to do this stuff I am so lost... please :)

 

[PhanthomJay]

i have this big assignment to do at school and i can't work out how to find the breaking and reaction distances ... i have a Vi = 0 Vf= 69km/h

if the car is braking, the initial speed is 69 km/hr and the final speed when it comes to a stop is 0

reaction time= 0.78sec deceleration of 4.49m/s and my total distance i need to find if i go over is 41 m ... i was thinking of useig d=(1/2 (Vf+Vi)xT for my reaction

the speed during the reaction time is constant at 69 km/hr

and i don't know how to do the breaking ?? :/ can anyone give me any sujestions on how to do this stuff I am so lost... please :)

For the braking distance, use one of the kinematic equations where vi, vf, and a are known, solve for d. Then add up the 2 distances and see if the car could stop in less than or more than 41 m.