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# Help me on this one question please! (Physics/mechanics) watch

1. My homework is to do this short question in mechanics.. but I don't know how! Could you help?:

50J of work is done in stretching a spring to an extension of 3.5cm. Work out the average force applied.

(I've worked out the 'maximum' force which is 2900N, but they said I need to work out the 'average' force... how do i do this? Any help would be greatly appreciated, thanks!)
2. I think what the question expects you to do is either divide the answer you got for the maximum force by 2. Since the force goes from 0->2900 as a straight line.

Or, I guess you can assume that the force is constant (which we know it isn't), and just do W=Fd, which gets you the same result as above.
3. (Original post by StayWoke)
I think what the question expects you to do is either divide the answer you got for the maximum force by 2. Since the force goes from 0->2900 as a straight line.

Or, I guess you can assume that the force is constant (which we know it isn't), and just do W=Fd, which gets you the same result as above.

Thank you for the reply! It turns out all I had to do was divide the work done by the distance *facepalm* im an idiot!
4. work = average force* distance
5. Physics major here This kind of problems require you to suppose that even if the force applied during the movement may vary and should be calculated instant by instant, there's an average force (this applies even to those situations where you have collisions and impulse: the force will vary, but thanks to the "mean value theorem" you can work out an average foce https://en.wikipedia.org/wiki/Mean_value_theorem).
So i'd say that you have:

W = F * d -> F = W / d = 50 / 0.035

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