Help couple questions?

[fungulo]

1.To avoid a potential collision with wildlife crossing the road, the driver of a car travelling 105 Km/h fully applies the brakes to stop as quickly as possible. If the car stops 3.8 s after the brakes are applied, what is the braking distance?

 

2.A vehicle comes to a stop 10.0 s after the brakes are applied. While the brakes were applied, the vehicle travelled a distance of 75.0m. If the vehicles acceleration remained constant during the braking, what was the vehicles initial speed?

 

3.Based on a reaction time of 1.50 s and a braking rate of -5.85 m/s, the stopping distance of a vehicle travelling 90 Km/h would be?

 

4.A high performance car initially travelling 97.2 Km/h came to a stop in just 2.9 s. The mass of the car and its contents was 1850 kg. what was the magnitude of the average net force (braking force) on the car while it decelerated?

[Bignose]

As this sure looks like homework, and the forum rules prohibit giving answers directly to homework questions, I will only provide generals hints. Do feel free to post what work you have done and members can help check your work, but do not expect your work to be done for you.

 

a) You have to make an assumption that the acceleration will be constant. Based on the the relationship between acceleration and velocity, you should be able to answer this.

 

b) This one uses the relationships between acceleration, velocity, and distance.

 

c) see b)

 

d) in addition to comments about b) this one also uses the relationship between force and acceleration.

[5614]

This thread is a duplicate with this one.