## Deceleration help! (Physics)?

Question

Eric is traveling at 30m/s. He runs out of gas and decides to coast to a stop. He does so over a distance of 225 meters. How long will Eric coast before coming to a stop? What is the rate at which Eric is accelerating to a stop?

Update: How long will Eric coast before coming to a stop?

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General Physics
4 years
1 Answer
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## Answer ( 1 )

Use the following equation to determine the acceleration.

vf^2 = vi^2 + 2 * a * d

0 = 30^2 + 2 * a * 225

450 * a = -900

a = -2 m/s^2

Use the following equation to determine the time.

vf = vi + a * t

0 = 30 + -2 * t

t = 15 seconds