How do I calculate the average deceleration of a car?

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SUMMARY

The average deceleration of a car traveling at an initial speed of 13 m/s, which comes to rest over a distance of 640 meters, is calculated using the formula v² = u² + 2as. By substituting the known values, the correct rearrangement yields an average deceleration of approximately 0.1 m/s². The calculation confirms that the average deceleration is derived from the equation a = (u² - v²) / (2s), where v is the final velocity (0 m/s), u is the initial velocity (13 m/s), and s is the distance (640 m).

PREREQUISITES
  • Understanding of kinematic equations, specifically v² = u² + 2as
  • Basic knowledge of physics concepts such as velocity and acceleration
  • Familiarity with unit conversions in physics (e.g., m/s to m/s²)
  • Ability to rearrange algebraic equations
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  • Study the derivation and application of kinematic equations in physics
  • Learn about different types of acceleration and deceleration in motion
  • Explore real-world applications of average deceleration in automotive engineering
  • Practice solving problems involving motion with varying initial speeds and distances
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This discussion is beneficial for physics students, automotive engineers, and anyone interested in understanding motion dynamics and calculating deceleration in real-world scenarios.

hellothere.
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Sorry about this, must seem a trivial question, but anyways here goes.

A car is traveling at 13ms^1. It is allowed to slow down natrually without appyling the brakes. The distance traveled in coming to rest is 640m.

Show that the average deceleration of the car is about 0.1ms^2.

-------------------

Ok so first of since time aint metioned i used.

v^2 = u^2 + 2as

giving me

v = 0
u =13
a = ?
s = 640

----------------------------------
v^2 = 13^2 + 2(a)640.

v^2= 13^2 +2(640)
___________
a

a * v^2 = 13^2 +2(640)

a = 13^2 +2(640)
__________
v^2

Giving me a very strange answer, no were remotely close to 0.1, I've obviously screwed up the re-arranging or used the wrong formula.

Would like a nudge in the right direction please.
 
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Welcome to PF.

Your equation is ok. But solving it looks not right.

V² = V² + 2*a*x

13² = 2 * a * 640

a = 169/1280
 
LowlyPion said:
Welcome to PF.

Your equation is ok. But solving it looks not right.

V² = V² + 2*a*x

13² = 2 * a * 640

a = 169/1280
Cheers, knew i did something wrong, thanks.
 

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