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- Thread starter zachcumer
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dx

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If the ball starts from rest and has a constant acceleration, the distance travelled is proportional to the square of the time since it started. So, say it travels 1 m in 1 second, then it will travel 4 meters in 2 seconds. Not 4 meters in the 2nd second. In the 2nd second, it will travel 4 - 1 = 3 meters.

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malty

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IF the total length of the plane is 25m, then clearly after travelling 25m the acceleration of 2ms^-2 will no longer be the case.So after 5 seconds the acceleration will be different. Are you given the balls initially velocity or do we assume it to be zero? Would you mind to quote the full question.

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IF the total length of the plane is 25m, then clearly after travelling 25m the acceleration of 2ms^-2 will no longer be the case.So after 5 seconds the acceleration will be different. Are you given the balls initially velocity or do we assume it to be zero? Would you mind to quote the full question.

At rest. it says!

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dx

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can you see my pic.

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malty

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I followed this formula: d = 1/2 * (A) * T^2

Here is the picture given: look at attached.

First off, that assumes initial velocity to be zero, and that formal gives the total distance travelled from 0 to whatever t may be:

say you take you look at five seconds

Then the d in your equation is the total distance travelled from 0 seconds through to five seconds.

It is NOT the distance travelled during the fifth second!

EDIT: Ahh I see dx has beat me here.

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- #10

malty

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To get the distance travelled in anyone second you find the d for t=x and t=x-1 and subtract the two:

Example

Your looking for the distance travelled during the 3rd second

Fill 3 and 4 in for t into your formula d=1/2at^2

and the difference in the two d's is the distance travelled in the 3rd second.

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- #12

dx

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at is the velocity. Not the distance.

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malty

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4 metres in the second second!! In two seconds the ball has gone 6 metres!!! As dx pointed out that's a velocity [check the units]

You told us the formula d=1/2at^2 yet you used v=at?

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distance in 5 seconds = d = 1/2 * 2 * 5 * 5...

Because the ball has rolled for 5 seconds.

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dx

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Yes, thats right.

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V = at.

A = 2 meters in one second.

T = I dunno, 2 seconds.

2 * 2 = 4...

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dx

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Look At The Picture!

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dx

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[tex] s = \frac{1}{2} a t^2 [/tex].

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- #22

malty

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[tex] s = \frac{1}{2} a t^2 [/tex].

That's the distance travelled after t seconds have passed! It's not the distance travelled at each second, the distance travelled at each second is the difference between say t=5 and t=4 plugged into that formula to get the distance travelled during the fourth second.

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- #24

dx

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That's the distance travelled after t seconds have passed! It's not the distance travelled at each second, the distance travelled at each second is the difference between say t=5 and t=4 plugged into that formula to get the distance travelled during the fourth second.

Exactly. Thats what I said, and what I have said 2 times before in this thread.

- #25

malty

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Exactly. Thats what I said, and what I have said 2 times before in this thread.

Hate to be picky but that was what you said until:

You can find the distances ateachsecond from the formula

[tex] s = \frac{1}{2} a t^2 [/tex]

Then you contradicted yourself :P but I know what you meant, I just was pointing it out in case zach followed it.

It's all cool I hope :)

*Like the sig by the way*

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