# Thread: Need help with algebra based physics problem

1. ## Need help with algebra based physics problem

A cook holds a 2.00 kg carton of milk at arm's length. What force B must be exerted by the biceps muscle? (Ignore the weight of the forearm.)
1 N

I have been trying for a while to figure this one out and its just not coming to me. I know the answer is supposed to be 312N. Any help would be appreciated. Thanks.

2. First, this has nothing to do with "Linear and Abstract Algebra" and does not belong in this category.

Second, draw horizontal and vertical lines making a right triangle with $\displaystyle \vec{F}_B$ as hypotenuse. The vertical side is a "near side" to that 75 degree angle and will have magnitude $\displaystyle F_B cos(75)$. In order to support the milk carton, we must have $\displaystyle F_B cos(75)= 2.00$. Solve that for $\displaystyle F_B$.

That will give the force in "kg" which is really a mass. To get the force in Newtons, multiply by g= 9.81[/tex].

3. 1) Why is this in Abstract Algebra. It's a physics problem. Trigonometry at worst on this one.

2) Have you identified that you are dealing with a Type 3 Lever? That would be a good place to start.

3) What forces must be equal? 2 kg * (25 cm + 8 cm) should be related to (sine or cosine of 75º) * (bicep force) * (8 cm)

I'll leave the details to you. Let's see what you get.