# Warm-Up Exercise for lecture 3

## Due 8:00 am, Tues, Sep 8

Physics 105, Fall 2009

Enter your 3-digit class identification number:

Enter the last 4 digits of your BYU ID:

Did you complete the reading assignment? (Typically this means at least 20-30 minutes looking over the assigned sections of the book.)
yes no

T/F: It doesn't matter which order you add two vectors together, you will get the same sum either way.
true
false

Which geometrical shape does the path of a 2D projectile follow?
line
circle
ellipse
parabola
hyperbola

A man on a treadmill is walking at 1.5 m/s to the left. The treadmill is going at 2 m/s to the right. If you are standing still, it looks like the man is moving:
0.5 m/s left
3.5 m/s left
stationary
0.5 m/s right
3.5 m/s right

Ralph is confused about how his book defined the components of a vector. The book says, "The components of a vector are the projections of the vector along the coordinate axes". What can you tell Ralph to help him understand what the word "projections" means in this context?

The comments in the next next two boxes go into a big, mostly anonymous text file that I skim through before the morning lecture, using the comments to help me plan class discussion. ("Mostly anonymous", because I can track down who made what comment, but it takes some effort on my part to do so.) Therefore, if you really want to make sure I see your question/comment and answer it individually, you should send it to me via email and not through this form.

Which part of today's assignment was particularly hard or confusing? What would you like to spend extra time on in class?