Journal 11/20

1. Why is the object of interest drawn as a dot?

The object of interest is drawn as the dot because the object is what is being acted upon.

2. How do you know how long to draw the arrows attached to the dot?

You know how long to draw the arrows attached to the dot by how much force is being pushed upon the crate. The two forces, the force of the floor on the earth and floor on the crate should be equal.

3. Why is there no arrow labelled F(man on crate) in the force diagram in the video?

The man is not creating an exerting force on the crate, the earth is.

4. In general, what can you tell about the object of interest by examining a complete force diagram?

The crate is at equilibrium at a vertical standpoint however, horizontally the crate is being forced in a direction.

5. In general, what can you NOT tell about the object of interest by examining a complete force diagram?

Whether the object of interest's velocity when moving will accelerate or not.

6. What do you know (and what do you NOT know) about the MOTION of the object shown in the force diagram below?



What is known about the motion of object is that it is not moving vertically because there are two forces that are equal. What is also known is about the motion of this object is that it is moving in a direction (right) because there is only one force acting upon it. What is not known about the motion of the object is the velocity of it's motion.

Journal 10/29

In agreement with Jenny. The green car overall has the highest ending velocity, but although the pink and blue car had greater acceleration rates, the ending velocity was nowhere near the same.

Pat thinks the cars stop at 17 seconds because the last car no longer accelerates after 17 seconds. He is not aware that although the cars are no longer accelerating, it does not necessarily mean that the cars are not moving. Velocity still exists however there is no change.

The pink car has the greatest change in position during the time interval t=3 and t=5. The reason for this is because the pink car's velocity is 30 m/s while the others are only 12 m/s (Green) and 15 m/s (Blue)