Physics

A driver of a car going 90.0km/h suddenly sees the lights of a barrier 40.0 metres ahead. It takes the driver 0.75 seconds before she applies the brakes, and the average acceleration during braking is -10.0 m/s squared. Does the car hit the barrier?SHow all your work. (2 parts)

  1. 👍
  2. 👎
  3. 👁
  1. V = 90km/h = 90km/h / 3600s/h = 0.025km/s = 25m/s.

    d = 25m/s * 0.75s = 18.75m = Distance
    traveled before brakes are applied.

    d = 40 - 18.75 = 21.25m = max stopping
    dist.

    Vf^2 = Vo^2 + 2ad = 0,
    (25)^2 + 2(-10)d = 0,
    625 - -20d = 0,
    -20d = -625,
    d = -625 / -20 = 31.25m = Distance traveled after brakes are applied.

    The car will hit the barrier, because it was required to stop within 21.25m
    after the brakes are applied.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    A car is traveling at 11.0 m/s, and the driver sees a traffic light turn red. After .59 s (the reaction time), the driver applies the brakes, and the car decelerates at 8 m/s^2. What is the stopping distance of the car, as

  2. Physics

    The speed limit in a school zone is 40km/h. A driver traveling at this speed sees a child run into the road 13m ahead of his car. He applies the breaks, and the car decelerates at uniform rate of 0.8m/s². If the driver's reaction

  3. physics

    A car is traveling 20 m/s when the driver sees a child standing on the road. He takes 0.8 s to react, then steps on the brakes and slows at 7.0 m/s2. How far does the car go before it stops?

  4. physics

    a driver in a car traveling at a speed of 21.8 m/s sees a cat 101m away on the road. How long will it take for the car to accelarate uniformly to a stop in exactly 99m?

  1. Physics

    A car is behind a truck going 18 m/s on the highway. The car's driver looks for an opportunity to pass, guessing that his car can accelerate at 0.6 m/s2 and that he has to cover the 20-m length of the truck, plus 10-m extra space

  2. physics

    Unit 2: Kinematics in 1-D Exam Preparation 1. A bike first accelerates from 0.0 m/s to 5.0m/s in4.5 s, then continues at this constant speed for another 4.5 s What is the total distance traveled by the bike? A car traveling at 20

  3. physics

    The driver of a car, traveling at a constant 25 m/s, sees a child suddenly run into the road. It takes the driver 0.45s to hit the brakes. As it slows, the car has a steady acceleration of 8.5 m/s^2. What's the total distance the

  4. Physics

    A car traveling 56 km/h is 22.0 m from a barrier when the driver slams on the brakes. The car hits the barrier 2.15 s later. (a) Assuming constant acceleration, what was the magnitude of the car's acceleration before impact?

  1. physics

    Suppose a car is traveling at +22.3 m/s, and the driver sees a traffic light turn red. After 0.351 s has elapsed (the reaction time), the driver applies the brakes, and the car decelerates at 8.00 m/s2. What is the stopping

  2. Physics

    A car is initially travelling at a constant speed of 20 m/s along a highway. Suddenly, the driver applies the brakes, causing the car to accelerate at -5.0 m/s^2. If the driver applied the brakes 0.50s late, determine the distance

  3. physics

    A car is traveling 15 m/s when the driver sees a child standing on the road. He takes 0.8 s to react, then steps on the brakes and slows at 8.0 m/s2. How far does the car go before it stops?

  4. Physics

    A car is traveling 28 m/s when the driver sees a child standing on the road. He takes 0.8 s to react, then steps on the brakes and slows at 7.0 m/s2. How far does the car go before it stops?

You can view more similar questions or ask a new question.