Hi there, I am a grade 11 student, learning physics.(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

A driver of a car going 90km/h suddenly sees the lights of a barrier 40.0 m ahead. It takes the driver 0.75s before he applies the brakes and the average accelleration during braking is -10.0m/s2.

a) Determine whether or not the car hits tha barrier.

b) What is the maximim speed at which the car could be moving and not hit the barrier at 40.0 m ahead? Assume the accelleration does not change.

a) Treat toward the barrier as positive.

v2=0m/s delta(t)= 40

v1=25m/s

a=-10m/s2

I am not quite sure how to do b)

2. Relevant equations

v2^2 = v1^2 + 2a(delta(d)) <---- a)

3. The attempt at a solution

I have already determined that it would take the car 50 m to come to a complete stop, so it would hit the barrier.

I am having trouble with b)

thanks in advance.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Will the car hit the barrier?

**Physics Forums | Science Articles, Homework Help, Discussion**