# science/math

A car traveling at the speed of 30.0 m/sec encounters an emergency and comes to a complete stop. how much time will it take for the car to stop if its rate of deceleration is -4.0 m/sec

1. 👍 0
2. 👎 0
3. 👁 322
1. Using Calculus

a = -4
v = -4t + c
when t=0 , v = 30
30 = 0 + c
v = -4t + 30

s = -2t^2 + 30t + k
when t = 0 , s = 0, so k = 0

s = -2t^2 + 30t

when the car stops, v = 0
4t = 30
t = 30/4 = 7.5 seconds

when t = 7.5
s = -2(7.5)^2 + 30(7.5) = 112.5 m

1. 👍 0
2. 👎 0
posted by Reiny

## Similar Questions

1. ### science

am confused. don't know what formula to use for this problem. A car traveling at a speed of 30.0m/s encounters an emergency and comes to a complete stop. How much time will it take for the car to stop if it decelerates at -4.0m/s?

asked by taylor on September 17, 2014
2. ### math

a car is traveling at a speed of 30.0m/s encounters an emergency and comes to complete stop how much time will it take for the car to stop if it decelerates -4.o m/s^2

asked by Anonymous on October 9, 2013
3. ### transportation engineering

on the same Lane of a road a car A is following car B at a center distance of 25 m. both cars are traveling at a speed of 100 kmph when car A attempts to overtake car B at a uniform acceleration of 0.8 m/s^2.after traveling for 5

asked by rajat on April 9, 2016
4. ### Science/Math

A car is travelling at a speed of 30.0m/s encounters an emergency and comes to a complete stop. How much time will it take for the car to stop at -4.0m/s^2

asked by Josh on April 22, 2016
5. ### physics

A 250 kg car starting from rest is pushed 30m. When the car reaches 30m, it’s traveling at a speed of 12m/s and it encounters 52N of friction. What is the acceleration of the car and what is the force of the push on the car?

asked by Alyssa on December 1, 2010
6. ### Algebra

The distance required for an emergency stop for a car varies directly as the square of the car’s speed. A car traveling at 50 mph requires 140 feet to stop. What is the stopping distance for a car traveling at 30 mph? What is

asked by Elena on October 22, 2011
7. ### Science

#1. Kilometers per hour describes the speed of an object. ture false **** #2. Which of the following reference points would allow you to observe the speed of a car that you are traveling in? a) an airplane flying across the sky b)

asked by Mindy on February 27, 2014
8. ### science

If you were riding on a train, which of the following would look as if it is not moving? the conductor walking by you a building you are passing a flying bird

asked by Anonymous on April 13, 2014
9. ### inter Algebra

Pick a car and find its top speed. Assuming that your chosen car reaches its top speed at the top of a ramp, leaving the ramp vertically 20 feet about the ground: 1.) When will the car land back on the ground? 2.) When would the

asked by linda on November 14, 2010
10. ### physics

a) calculate the acceleration of a 0.55-m-diameter car tire while the car is traveling at a constant speed of 25m/sec. b) compare this with acceleration experienced by a jet car tire of diameter 1.0m when setting a land speed

asked by lucy on September 26, 2011

More Similar Questions