# What students find confusing and interesting

Here are snippets from students’ writing about what is confusing and interesting during the semester. Enjoy!

The most confusing thing about Newtons’ third law is that action and reaction forces occur simultaneously at the same time. How do they happen at the same time?

It is interesting how static friction is greater than kinetic friction. Thus, explaining why it is easier to keep a box moving than it is to start it moving.

I like seeing that the problems build off things we already learned. We have to incorporate kinematics into force problems so it keeps me from forgetting things and also shows me the big picture of why we learned it in the first place.

The topic I found most interesting the acceleration on an inclined plane as its interesting in splitting up the weight into two forces and being able to calculate the acceleration with trigonometry. I like to be able to really see how trigonometry can work in real situations such as calculating acceleration as in Figure 3.23.

The most interesting to me is Newton’s Second Law and I think the reason why is because it makes sense and I understand it!

The interesting part of the reading and the example problems and sections is how all of what we have learned in the reading before is found in almost every problem in order to work it out.I think its interesting how there is always a Free body diagram used in almost all problems and how there is always acceleration and velocity in every problem. Its interesting to see Newtons laws applied to every problem done in class and seen in the examples.

I still find it fascinating how the concepts all come together like a big puzzle. I understand why some higher level math is important to learn before getting involved in the concepts in physics. It is like building a car engine. Without all the pieces the engine may not make the car run, but with all the pieces perfectly aligned the engine will be amazing for the car.

The most interesting thing that I found in the assigned reading was the fact if a cart was going down a ramp and suddenly the incline vanished, the cart would experience free fall. I guess I just never genuinely thought about what would happen if you were to take away that angle.

I find it interesting that when an object is on an incline, we can change the x and y axis to match the incline.

The topic that I found that was most interesting was the use of trigonometry in physics. I find it interesting that all of this stuff go well together and that 3 +4 can equal 5.

Realizing that the combine force of the tension force and the normal needed to equal the weight force. For the group problem in class on Thursday, I initially thought that we could find normal force by using the Pythagorean theorem to find the numerical value for normal force. However, one of the group members explained that since the normal force arrow and the tension force arrow would not form a triangle therefore the Pythagorean theorem could not be used to find normal force. To calculate normal force we had to subtract the tension force from the weight force.

The topic that I found most interesting was one of the topics I found to be most confusing, which was the elevator scenario and its sensations. It is interesting to see why we feel the way we do when riding an elevator, whether that being we feel lighter or heavier during our elevator ride. It is also interesting to see and think about scale measurements on an elevator, and how we can apply our knowledge of forces to justify these happenings.

I think it is very interesting that scales measure apparent weight and not your actual weight. The fact that you can change a reading on a scale or that you are weightless in free fall is very interesting.

The most confusing part of class so far for me is the velocity vs time graphs and the position vs time graph. I have a hard time with graphs in general, so in class I am getting them confused and putting/drawing the wrong things down. Nothing else is confusing to me about the lecture, but I do need more practice with graphs.

The sign of acceleration can be confusing, since it is natural to think that speeding up would mean positive acceleration, and slowing down would mean negative acceleration. Since that is not necessarily the case, I would like to talk about the way direction affects the sign of acceleration, in a way that makes it easily understandable.

I am having a hard time understand acceleration with velocity-versus-time graphs. Also understanding the whole concept behind the slope of the velocity-versus-time graph regarding acceleration. Understanding that acceleration as the slope of the velocity graph forces us to pay careful attention to the sign of acceleration. An object undergoing constant acceleration has a straight line. However, a straight line can be towards the positive or negative direction so it then changes the whole interpretation of the graph in assessing acceleration. Reading velocity-versus-time graphs and applying that information to the concept of acceleration.

I found it very interesting that all of the areas under the velocity vs time graphs can be divided into triangles and rectangles to find the total area underneath. This really simplifies the process and takes a concept that seems scary and breaks it down into simple geometry.

Acceleration in general in interesting to me. It is nature to thing when an object is speeding up with would automatically have positive acceleration and negative acceleration when slowing down. After class I now realize that this is not the case and that direction is actually a very important concept. Knowing rather an object is speeding up or slowing down and which direction it is traveling in will in fact lead you to rather the acceleration is positive or negative.

The topic that I found most interesting was honestly how much information you could get from a velocity vs. time graph. I mean, ultimately, you can find the position, distance, displacement, acceleration–pretty much everything we have talked about so far.

The topic that I had enjoyed the most would be that the velocity is the slope of the position versus time graph and that the acceleration is the slope of the velocity versus time graph. I find that interesting that those three go hand in hand. I also find it interesting that you can find the acceleration, velocity and the displacement just by looking at the velocity versus time graph. There are so many ways to acquire data by just one or two graphs.

The topic that I found to be most interesting was the concept of constant acceleration in the example of the rocket as the rocket has a constant velocity but the acceleration is zero, so the relationship is similar to the position and time graphs to velocity and time graphs. I like looking at similar relationships and this made my understanding of acceleration better.

I found interesting how the acceleration vector has an easy way to remember in which direction it goes. When the velocity is speeding up the vectors of acceleration and velocity are in the same direction and when the velocity vectors are slowing down the acceleration and velocity vectors are going in different directions.