Pre-class warm up questions 

1. An object moving away, speeding up.
2. An object moving away, slowing down.
3. An object moving towards, speeding up.
4. An object moving towards, slowing down.

1. A,1,3 Moving away causese both the velocity and acceleration graphs to be positive. Speeding up causes the velocity graph to have a positive slope. The acceleration graph can be 1 or 3 because we don't know if the acceleration is constant or not.

2. B,2,4 Moving away from the detector causes the object to have positive velocity; slowing down causes its graph to slope downward. Decelerating causes the acceleration graph to be negative; since we don't know if the deceleration is constant, the graph can be either 2 or 4.

3. C,2,4 The velocity graph wiil be negative since the object is moving towards the detector; speeding up causes the slope of the line to be negative. The acceleration graph will be negative since the object is accelerating in the direction of the detector; since we don't know if the acceleration is constant the graph can be 2 or 4.

4. D,1,3 The velocity graph will be negative because the object is moving towards the detector; the object slowing down causes the slope of the graph to be positive. (deceleration in the direction of the detector = positive) The acceleration graph will be positive because the object is decelerating in the direction of the detector. Since we don't know the rate of acceleration, the graph can be 1 or 3.

I would think the high acceleration is referring to stress on the joints. The stress would be caused when the weight of the persons body pushed from one direction and has to be absorbed by the joint and the ground or whatever the person is exercising on.

These high accerleration injuries occur when the body is moving at a high speed in one direction, and then a sudden stop and change of direction is put on the joint.

• I found that there are no examples of the graphs that pertain to our homework in the reading.
• The only thing i found difficult was that the reading didnt give very good discriptions of hows graphs would look compared to the type of motion.

• So far I haven't found the material extremely difficult. The incorporation of the motion sensors into the first two labs was really interesting. I liked how we could make our own movements and thus create our own position/velocity graphs, instead of reading a description of movement and corresponding graph in a book.
• i would really like it if we could have a lecture to this class. it seems like all we do is labs. PLEASE have a lecture telling us the fundimentals of this stuff. from the opinion of someone that has never had physics before this is hard stuff to learn on your own. graphs and experiments do help alot, but we need some tought structure before we can apply this stuff in our labs.

• I had fun once again doing the lab with the motion sensors, and I thought it was cool bringing the aspect of the carts into it and dealing with acceleration.

• I am having a little more trouble understanding the acceleration graph. For some reason it is just not clicking.
• I find it very confusing to correspond velocity graphs with acceleration graphs.
• Im kinda confused about the acceleration graphs. I'm not really clear because i don't see how you can have a negative acceleration like we got on the motion detectors today on the lab.
• What I found most confusing is trying to diferentiate in my mind the difference between velocity and acceleration. I know what these differences are, but when trying to look at greaphs, it is hard and I really have to think about it.
• I need some moer help with the relationships of position velocity and acceleration.
• I still don't understand these acceleration/time graphs. I understand the position/time graphs intuitively, and the velocity/time graphs through expirimentation, but these acceleration graphs are giving me lots of trouble.
• Some of the graph seem to still be confusing comparing the acceleration to the velocity graphs.
• I thought that the acceleration lab was much more difficult than the previous labs. I still dont quite have a grasp for the acceleration graphs like I do for the velocity and position graphs.
• It was difficult to figure out why the acceleration graph was the way it was, but I was finally able to make sense of it.
• I am still having a little confusion between all the types of graphs. I think it would help to keep going over the relationships between all the graphs.
• The relationship with velociy and acceleration for an object moving in space in confusing just in finding the least acceleration vs the least velociy.
• i am having a little difficulty ditinguishing the diference between velocity and acceleration, and they way they relate to each other.
• When I was working on the lab, I am still feel very confused on the acceleration graph. Whatever we predicted on the acceleration, it came out to be wrong.