- #1

thschica

- 47

- 0

If she hits the brakes, how far will she travel before stopping?

19 m (I know how to do this one )

If she hits the gas instead, how far will she travel before the light turns red?

? m (How would I do this one?)

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- Thread starter thschica
- Start date

- #1

thschica

- 47

- 0

If she hits the brakes, how far will she travel before stopping?

19 m (I know how to do this one )

If she hits the gas instead, how far will she travel before the light turns red?

? m (How would I do this one?)

- #2

arildno

Science Advisor

Homework Helper

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Dearly Missed

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How can you find her possible acceleration from this piece of info?

- #3

Fermat

Homework Helper

- 872

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13 km/h = 13/3.6 = 3.6 m/s

So, accln is 3.6/3.9 = .925 m/s²

- #4

Fermat

Homework Helper

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You know the accln.If she hits the gas instead, how far will she travel before the light turns red?

? m (How would I do this one?)

You know her initial speed.

You know the time limit during which she can travel.

Use the suvat eqn for distance traveled under constant accln.

- #5

thschica

- 47

- 0

a=.93

Initial speed =15.83

time = 2secs

is that right? I just can't seem to get the right answer.

Initial speed =15.83

time = 2secs

is that right? I just can't seem to get the right answer.

- #6

Fermat

Homework Helper

- 872

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That's right - you should have used the eqn: s = ut + ½at².

If you used that, what did you get.

If you used that, what did you get.

- #7

thschica

- 47

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Is the correct answer 33.52 ?

- #8

Fermat

Homework Helper

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a = 0.923 m/s²

u = 15.83 m/s

t = 2 s

s = ut + ½at²

s = 15.83*2 + ½*0.923*4

s = 31.66 + 1.846

s = 33.506 m

========

- #9

thschica

- 47

- 0

Thanks a lot for everything!

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