To stop a car, first you require a certain reaction time to begin braking. Then the car slows down at a constant rate. Suppose that the total distance moved by your car during these two phases is 56.7 m when its initial speed is 85.0 km/h, and 24.4 m when the initial speed is 52.8 km/h.
(a) What is your reaction time?

(b) What is the magnitude of the deceleration?

  1. 👍
  2. 👎
  3. 👁
  1. 85.0 km/h = 23.61 m/s
    52.8 km/h = 14.67 m/s
    Total distance = reaction time distance + braking distance
    = V*t + V^2/(2a)
    Write two equations in two unknowns and solve for the two unknowns, a and t.
    56.7 = 23.61 t - (23.61)^2/(2a)
    24.4 = 14.67 t - (14.67)^2/(2a)

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Math

    The distance require to stop a car varies directly as the square of its speed. If 250 feet are required to stop a car traveling 60 miles per hour, how many feet are required to stop a car traveling 96 miles per hour!

  2. Science halp

    6.Two cars with different masses travel at the same speed down a hill toward a stop sign. What will happen when both cars apply brakes at the same time to stop? * A. The car with the smaller mass will require less force to stop

  3. physics

    A car of mass 1100 kg that is traveling at 27 m/s starts to slow down and comes to a complete stop in 578 m. What is the magnitude of the braking force (in N) acting on the car?

  4. Maths

    The braking distance of a car is directly proportional to te square of it's speed. When the speed is p metres per second, the braking distance is 6m. When the speed is increased by 300%, find (a) an expression for speed of the car

  1. Physics

    A car with good tires on a dry road can decelerate at about 5.0m/s/s when braking. If the car is traveling at 55miles/hour, how much time does it take the car to stop? 55 mph = 80.7 ft/s = 24.6 m/s Divide the initial speed by the

  2. physics 1

    In coming to a stop a car leaves skid marks 92m long on the highway. Assuming a decceleration of 7.00m/s^2, estimate the speed of the car just before braking.

  3. physics

    A force of -9000 N is used to stop a 1500kg car traveling at 20 m/s. What braking distance is needed to bring the car to a halt?

  4. physics

    You are driving through town at 14 m/s when suddenly a car backs out of a driveway in front of you. You apply the brakes and begin decelerating at 3.3 m/s2.How much time does it take to stop? After braking half the time found in

  1. Driver's Ed

    1. The natural laws include the law of (1 point) speed limits. gravity*** railroad crossings. yielding. 2. Which of the following should determine whether you need to speed up or slow down? (1 point) how quickly you need to get

  2. Physics

    You are driving down the highway late one night at 20 m/s when a deer steps onto the road 35 m in front of you. Your reaction time before stepping on the brakes is 0.50 s , and the maximum deceleration of your car is 10 m/s2 . How

  3. Physics

    Two cars are driving at the same constant speed on a straight road, with car 1 in front of car 2. Car 1 suddenly starts to brake with constant acceleration and stops in 10 m. At the instant car 1 comes to a stop, car 2 begins to

  4. physics

    You are driving to the grocery store at 20 m/s. You are 110 m from an intersection when the traffic light turns red. Assume that your reaction time is 0.70 s and that your car brakes with constant acceleration. How far are you

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