# Homework H.2.F Discussion As you plan your solution, consider that for the velocity part of the problem, you will need to use a velocity equation for bar AB and two velocity equations for the disk:

• Write the velocity of point B referenced to point A on bar AB.
• Write the velocity of point O referenced to the contact point C on the disk. Note that since the disk does not slip, the velocity of point C is zero.
• Write the velocity of point B referenced to point O on the disk.

These equations together will provide you with the equations that you need for the angular velocities of the bar and disk.

Repeat this same process above for accelerations. Please note that the acceleration of C on the disk is NOT zero - instead, you know that its acceleration is strictly in the y-direction.

## 5 thoughts on “Homework H.2.F”

1. Chick-fil-A Official says:

From the hint, I know the velocity of C is zero, but why is the acceleration of C strictly in the y-direction?

2. CMK says:

Chick-Fil-A: Recall for no slipping on a fixed surface, the components of velocity and acceleration of the contact point along the fixed surface (i.e., the x-direction) must be zero. As shown in the Challenge Question on pp. 91-92 this no-slip condition then says that the component of velocity in the y-direction is also zero, but the y-component of acceleration is NOT zero. Therefore, the acceleration of C above is strictly in the y-direction.

3. KT says:

To solve for angular acceleration of AB, I have the y-direction equation which includes two unknowns: angular acceleration of AB and acceleration at C. How do I solve for the acceleration at C?

1. Cullen Barber says:

You know that the acceleration of O in the j_hat direction must equal 0, so you can set the j_hat component of the acceleration of O to be equal to 0, then solve for the acceleration of C. @KT

4. Joshua says:

IS there a good example video that corresponds to this question?