Impulse momentum theorem is one of the fundamental principles of physics, especially in mechanics. Therefore, students' understanding of impulse and momentum will contribute to their success in learning physics. This study exposed common students difficulties in solving problems related to impulse and momentum. The subjects consisted of 175 students of a Senior High School in Malang, 70 students of grade XI who recently learned about impulse and momentum and 105 students of grade XII who relearned the topic for national examination preparation. The data were gathered using multiple-choice test with open explanation and confidence rating scale. The study concluded that the students' difficulties were not only caused by their lack understanding of the concepts but also by their deficiency in using vectors.

Peneliti melakukan penelitian pengembangan dan penggunaan instrumen diagnostik three-tier dengan tujuan untuk megidentifikasi miskonsepsi yang dimiliki siswa pada materi fluida statis. Penelitian yang dilakukan merupakan penelitian pengembangan. Subjek penelitian dalam penelitian adalah siswa kelas X MIA 4 MAN 3 Malang. Instrumen yang dikembangkan adalah instrumen diagnostik three-tier berjumlah 24 butir soal dengan 4 alternatif jawaban, 4 alternatif alasan pemilihan jawaban, dan keyakinan jawaban (yakin / tidak yakin) dengan 3 rentang tingkat keyakinan. Seluruh butir soal dinyatakan layak pada ranah materi, konstruksi, bahasa, dan kemampuan identifikasi miskonsepsi menurut penilaian ahli dengan nilai rata-rata diatas 3,26. Hasil identifikasi menunjukkan bahwa siswa yang mengalami miskonsepsi dan bahkan tidak memiliki konsepsi pada materi fluida statis masih cukup besar. Beberapa jenis miskonsepsi yang ditemukan diantaranya, siswa beranggapan bahwa (1) luas bejana mempengaruhi besarnya tekanan hidrostatis, (2) gaya yang diberikan pada fluida akan diteruskan ke segala arah sama besar, (3) gaya Archimedes dipengaruhi kedalaman benda dalam fluida. The researcher do research about development and application of three-tier diagnostic instrument to identify misconceptions within static fluid material. This research is due to research and development. The subject of the research is the student of 10th grade of mathematics and science 4 MAN 3 Malang. The instrument is three-tier diagnostic instrument that consist of 24 questions with 4 alternative answers, 4 alternative reasons, and the sureness of every answer (sure/not sure) with three different levels. The material, construction, language, and misconception identificational ability on every question are valid according to experts judgement with average score over 3,26. Identification's result shows that many students still get in misconception on understanding the static fluid material, even some of them don't understand at all. Sort of misconception's types that found are student belief that (1) area of the container has an effect on hydrostatic pressure, (2) force given to the fluid will be transferred in all direction propotionally, (3) Archimedes's force is influenced by the depth of object on fluid.