Analyzing Forces in Two Dimensions

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Students use vectors, trigonometry and Newton's 2nd Law of motion to analyze the forces on and motion of an object.

Big Idea

When analyzing forces, x and y force components can be analyzed independently.

Context and Supplies

I apply a flipped classroom as a teaching strategy in this lesson. Students watch a 10 minute lecture on forces in 2 dimensions at home at their own pace. They are expected to take detailed notes from the video. In class, students apply what they learned on the video. I use a flipped classroom because students are comfortable learning from online videos. There is also the benefit that while they watch, they can pause and rewind sections as needed. When it comes time to apply the concepts, they are in the classroom where they can get the support from their peers or me. 

Because of the mathematics involved in the problems, CCSS Math Practice 2: Reason abstractly and quantitatively is applied along with NGSS Science Practice 5: Using mathematics and computational thinking. The content is all in the context of NGSS Performance Standard HS-PS2-1, the mathematical relationship between the net force acting on an object and its acceleration.

Students Apply Concepts Learned from Video

40 minutes

The objective for the class is projected on the board using the Forces in 2-Dimentions Power Point. It is to "Analyze the motion of an object that is being pulled/pushed at an angle using vectors, trigonometry and Newton's 2nd Law." I tell the students that now is the time to make a step closer to real life as we begin to analyze forces acting in two dimensions instead of just one!

I put the second slide of the Power Point on the board as a reference and hand out the Forces in 2-D Practice worksheet and instruct students that they have 30 minutes to complete this activity. Students use their notes from the video watched they watched the night before. I use this time to check the quality and completeness of their notes from the video and also offer any needed support on the worksheet. With my gradebook in hand, I review the notebook of every student in the class. I provide feedback on the quality of their notes, specifically if there is enough detail, the caution and care applied to their FBDs, and application of the concepts with examples given at the end of the video. I have the Solutions to Forces in 2-D Practice on hand so that I can tell the students if their answers are correct.

There are always a few students who did not watch the video or who watched the video but did not take notes. I give those students a zero for the homework grade and have them watch the video during class. They can use their smart phone or one of the class computers. They then have to come in during a free period to make-up the practice worksheet.

Review and Closure

10 minutes

The last 10 minutes of class is spent in review of the practice sheet. I find two students who did the work correctly and with excellence and have them display their work their work using the document camera. I prefer to ask students who do not typically raise their hands or have struggled in the past to provide an answer. This is a great opportunity to boost their confidence and to recognize their efforts. With the use of the flipped classroom, I can always find one or two students who meet this criteria.

Once we are done reviewing, my parting comment is to say that "The beauty and power of physics is that we can take complicated situations, break those problems into parts, analyze those parts individually, and then put it all back together to find the solution."  This happens frequently in my physics lessons and I repeat this theme. Before students depart, I hand out the Forces in 2-D Homework sheet and let students know that it is due the next day.