Force Necessary to Start Moving Crate: 167 N

[Pencil]

To move a large crate across a rough floor, you push down on it at an angle of 21°. Find the force necessary to start the crate moving, given that the mass of the crate is m = 32 kg and the coefficient of static friction between the crate and the floor is 0.57.

N=mg=(32)(9.81)= 313.92 * coefficaint of mew sub s=.57=178.9
Ok, I think I did that right...only I'm not sure what to do with the 21° angle. I did 178.9cos(21)=167.0 but that's not right.

 

[mbrmbrg]

Did you draw a diagram with the applied force resolved into x and y components? (BTW, that's where the angle comes in)
Because in this case, N does not equal mg.

 

[Pencil]

Like this?
Ny=N
Fky=0
Wy=-mgsin(21
Nx=0
Fkx=-mewk
Wx=0
I did Fk=mewkN=.57*(mgsin(21)=.57*112.5=64.12 I did somthing wrong...again...but I don't know what...

 

[mbrmbrg]

where's the force of the push? It has both an x and a y component.
But yeah, that's the sort of chart I had in mind. :grin: