Thread: Energy Question

I don't really understand energy in Mechanics, so please could you post up your working out as well

Answers;

Spoiler:

33.32, 40.2, 26.6, 6

Thanks in advance.

this can be done by the work - energy principle

1) when rope becomes taut, the potential energy stored on the point O is converted to the kinetic energy. (when the point where string become taut is considered as the datum level). so it's just E_p = E_k.

2)apply work-energy principle from point O to the point 4.4 below form the point O(take as A). Take A as the datum, so the potential energy at O is stored in the elastic string

3) you know the strain of the string so you can find the stored energy.

4)do the same thing that is done in the question 2), but in here there is an additional energy type apart from the elastic energy (ie kinetic energy). So take a point 3.2m below O as the datum and apply work-energy principle

Wnen the mass is released @o elevation it will accelerate to elev 1.7m unimpeded. At this level its kinetic energy will be converted to potential energyin the string.At elev 4/4m the line goes taut and downward motion stops.If the 2 Kg weight is replaced with a lighter weight ( restaining the loaded string) work can be done when the lower weight is released.For example the lower weight would shoot back




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