Tpr ch 3 practice question

[KVS]

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I'm having a hard time understanding inclines on the mcat. It was problem area for me in undergrad as well. Can someone please tell me how to answer this question, along with any tips to really understanding inclines?

Q: a box of mass 'm' is sitting on an incline of 45 degrees and it requires an applied force 'F' up the incline to get the box to begin to move. What is they maximum coefficient of static friction?

I think another problem I have is just working with and manipulating equations.. Any tips on this will also be greatly appreciated. Thanks!

 

[KVS]

Is that a w?
The answer is:
{([sqrt2]*F)/mg} - 1

I have NO idea how to get this answer

 

[KVS]

But gravity and friction are in the same direction. So the applied force has to overcome both of these in order to move. I understand this conceptually- I just need to know how to manipulate equations.. Anyone?

 

[312312312]

I was studying the same stuff not that long ago. I don't get it either lol

 

[KVS]

I see what i was doing. I was using the value of (sqrt2)/2 as the value for sin 45 and cos 45.. Instead of 1/(sqrt2). I think it's the same thing as saying (sqrt2)/2 though.