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Homework Statement
A crate with a weight of [itex]50N[/itex] rests on a horizontal surface. A person pulls horizontally on it with a force of [itex]10N[/itex] and it does not move. To start it moving a second person pulls vertically upwards on the crate. If the coefficient of static friction is [itex]0.4[/itex], what is the smallest vertical force which will move the crate.
Homework Equations
[itex]f_s=\mu_sn[/itex]
The Attempt at a Solution
[itex]R(\rightarrow): 10 - f_s = 0 \implies f_s = 10N[/itex]
[itex]f_s=\mu_sn_{tot} = (0.4)(n_{tot}) = 10 \implies n_{tot} = 25[/itex]
[itex]n_{tot} = F_y+n \implies F_y = 25-50 =-25N[/itex]
4. The problem I encounter
Can you check my method please. I got [itex]-25N[/itex] which is negative hence this is giving me a doubt. Thanks.
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