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#1 2007-03-09 07:31:20

bugman
Member
Registered: 2007-03-09
Posts: 6

need help

the question in the book states:

A 9kg hanging weight is connected by a stringover a pulley to a 5kg block that is sitting on a flat table.  if the kinetic friction is .200, find the tnesion in the string.

The answer in the book is 37.8 N

Can anyone help me to understand how this was gotten?

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#2 2007-03-09 10:08:11

JaneFairfax
Member
Registered: 2007-02-23
Posts: 6,868

Re: need help

Physics.gif

Let the tension in the string be T.

The acceleration for both blocks is the same; let it be a. Then the net vertical force on the 9kg block is 9a and the net horizontal force on the 5kg block is 5a.

From the diagram,

and

Hence

Now you can solve for T (taking g = 9.8 ms[sup]−2[/sup]).
­

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