(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Find the readings on each of the balances in these 4 situations (strings are massless and incline is frictionless):

(sorry about the photo - dont know how to fix it)

2. Relevant equations

F=ma, W=mg

3. The attempt at a solution

1) Seems easy enough. Im pretty sure the balance would just read98 Nsince the tension above equals the weight of the mass below.

2) Im having a little trouble with this one. I cannot tell if its going to be 196 N (98 N from each of the weight pulling down on each end) or just 98 N. Each of the blocks has a net force equation of:

F = W - T = ma

98 - T = 0

T =98 N(T, the tension, is what the scale will read, correct? Thats where the answer comes from?)

so I get the tention in the string is 98 for both but I dont know how to combine the two net force equations into a single answer for the balance reading.

3) the block has a net force equation of:

F = W - T - T = ma

W - 2T = 0

W = 2T

so the tension in the string/balance reading would be half of the blocks weight =49 N.

4) I know I need the component of the blocks weight on this one due to the incline. And that should be Wsin30 = 49.

so the net force equation here is:

F = Wsin30 - T = ma

T = Wsin30 =49 N

is that the correct answer? What about that other 10 kg block above? How does it get included into the problem (if at all?)

thanks.

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# Homework Help: Finding spring balance readings (newtons)

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