(Updated Tues, Jan 10th @ 10:42am)Problem statementSolution video |

**DISCUSSION THREAD
**

Please post questions here on the homework, and take time to answer questions posted by others. You can learn both ways.

(Updated Tues, Jan 10th @ 10:42am)Problem statementSolution video |

**DISCUSSION THREAD
**

Please post questions here on the homework, and take time to answer questions posted by others. You can learn both ways.

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Can someone explain how to find the unit vector on part b because the position vector is composed of both variables and numbers?

I believe for this problem you can use the direction angles strategy to find the unit vector. The first example from Period 2 shows how this can be done.

In what notes do we talk about the resultant and how to find it?

I don't think they do but I am pretty sure you find it by adding the force vectors

This is correct, the resultant (which is a vector) is just the sum of the force vectors.

How do we find direction cosines and direction angles with the d being in there since they don't cancel out?

nevermind I figured out where they cancel

On part b (finding unit vector), I used Φ direction angle to find out the projection of F(AD) onto the xz plane. And I noticed that there is no additional θ or other degree sign that i can use to figure out the unit vector for x,y,z...

Do i have to use only Φ direction angle to figure out the unit vector for x,y,z?

In the first example of 2nd period, there were two angle in the figure : Φ and θ...

The process I've been suggesting to students is to start with finding the length DO so that you can write the coordinates of point D. After you find that length you can do A-D to get the position vector, and use that to get the unit vector. This isn't the only way to do this problem, but it's a process that will always be applicable when finding a unit vector between two points.