Problem statementSolution video |

**DISCUSSION THREAD**

Ask and answer questions here. You learn from both.

* DISCUSSION and HINTS*As can be seen from the animation below, the path taken by P is a bit complex. However, what if we put an observer on the non-extending section of the rotating arm - what motion would the observer see for P? Think about that.

Suppose that we do put an observer on the non-extending portion of the rotating arm. That observer would describe the motion of P as being on a straight path aligned with the *x*-axis. Specifically, we have:

*( v_{P/O})_{rel} *=

*L_dot*

**i**

*(*=

**a**_{P/O})_{rel}*L_ddot*

**i**Using this observer, we can write down the velocity and acceleration of P using the moving reference frame velocity and acceleration equations:

**v**_{P} = **v**_{O} + (**v**_{P/O})_{rel} + **ω** x **r**_{P/O
}**a**_{P} = **a**_{O} + (**a**_{P/O})_{rel} + **α** x **r**_{P/O} + 2**ω** x (**v**_{P/O})_{rel} + **ω** x (**ω** x **r**_{P/O})

where * ω* and

*are the angular velocity and angular acceleration, respectively, of the observer.*

**α**