How do I calculate the average deceleration of a car?

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In summary, the conversation discusses a problem involving a car traveling at 13ms^1 and slowing down without applying brakes. The distance traveled in coming to rest is 640m and the goal is to find the average deceleration of the car. The equation v^2 = u^2 + 2as is used to solve the problem, but the solution is not correct. After receiving a nudge in the right direction, the correct solution is found to be a = 169/1280, which is approximately 0.1ms^2.
  • #1
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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  • #2
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
 
  • #3
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.
 

FAQ: How do I calculate the average deceleration of a car?

What is deceleration?

Deceleration is the rate at which an object slows down. It is the opposite of acceleration, and is measured in meters per second squared (m/s²).

How do you calculate deceleration?

Deceleration can be calculated by dividing the change in velocity by the change in time. The formula for deceleration is: a = (vf - vi) / t, where a is deceleration, vf is final velocity, vi is initial velocity, and t is time.

What units are used to measure deceleration?

Deceleration is typically measured in meters per second squared (m/s²), but it can also be measured in other units such as feet per second squared (ft/s²) or kilometers per hour squared (km/h²).

What causes deceleration?

Deceleration is caused by a force acting in the opposite direction of motion. This force can be friction, air resistance, or an opposing force from another object.

How does deceleration affect motion?

Deceleration causes an object to slow down and eventually come to a stop. It can also change the direction of an object's motion, as seen in circular motion or when turning a corner while driving.

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