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ire three significant digits. that WebAssign answers require three significant d

ID: 1437313 • Letter: I

Question

ire three significant digits. that WebAssign answers require three significant digits. Refer to procedure 2. Assume the mass of the cart is m, and the mass hanging on the end of the string, M, is the maximum mass needed to just balance friction. a) Suppose m 3 1806 g 75 g and M 758.0 g t 28.6 g. Find the coefficient of static friction between the cart and the surface us b) Suppose now that mass 778.0 g t 37.8 g is added to m, the mass of the cart. Find the new maximum mass M of the counterweight needed to just balance friction g t M

Explanation / Answer

a) on hanging mass M,

T - Mg = 0

T = Mg

on cart ,

in vertical, N - mg = 0

N = mg

frictionforce, f = us mg

in horizontal,

T - f = 0

T = us mg

hence, us mg = Mg

us = M / m

value of us = 758 / 1806 = 0.4197

&us = 0.4197 sqrt[ (28.6/758)^2 + (75/1806)^2 ] = 0.023


us = 0.4197 +- 0.023


b) M = us m = 0.4197 +- 0.023 [ (1806+-75) + (778.0 +-37.8)]

           = (0.4197 +- 0.023) ( 2584 +- 165.2 )


value of M = 1084.5


&M = 91.3


M = 1084.5 +- 91.3 g