- #1

aerograce

- 64

- 1

## Homework Statement

Two small balls, each of weight Wo, are supporting a big ball of weight W1, as shown in Figure Q2. The line connecting the center of the upper ball and that of a lower ball forms an angle of 45° with respect to the horizontal, as shown in Figure Q2. A block of weight Wo is placed on the right to prevent sliding of the balls. The vertical surface of the rectangle block is frictionless. The static friction coefficient equals μ between all balls and between the rectangle block and the bottom floor. Answer the following questions and express the answers in terms of Wo and μ. Make assumptions where necessary.

(a) Determine the minimum static friction coefficient between the bottom floor and the lower right ball for the system to be in equilibrium.

(b) Determine the maximum weight W1 that can be supported by the lower balls before sliding occurs.

## Homework Equations

f=μN.

## The Attempt at a Solution

Honestly, I have no thoughts about how to approach this problem. I am just thinking that, we should analyse the right ball, where it has a static friction μN, and N can be obtained by:

2Nsin(45)=W1;

And we use equilibrium for the right ball, and we will know the normal force it exerts on Wo. And we can then know the static friction coefficient by analyzing the block.

Can anyone give me more thoughts or inspirations to approach this problem?