Poking Your Finger into a Cup of Water on a Scale: Simple Adhesion Force Experiments

Autor/inn/en	Hull, Michael M.; Nakayama, Shizuka; Tosa, Sachiko
Titel	Poking Your Finger into a Cup of Water on a Scale: Simple Adhesion Force Experiments
Quelle	In: Physics Teacher, 61 (2023) 2, S.128-132 (5 Seiten)Infoseite zur Zeitschrift PDF als Volltext Verfügbarkeit
Zusatzinformation	ORCID (Hull, Michael M.) ORCID (Tosa, Sachiko)
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0031-921X
Schlagwörter	Science Instruction; Physics; Scientific Principles; Concept Formation; Scientific Concepts; Water; Science Experiments; High Schools; Secondary School Science; College Science + Suchen Sie Ihr Suchwort? Teaching of science; Science education; Natural sciences Lessons; Naturwissenschaftlicher Unterricht; Physik; Concept learning; Begriffsbildung; Wasser; High school; Oberschule
Abstract	Newton's laws are a ubiquitous topic in introductory physics instruction. One common problem involves asking what will happen if you stick your finger into a cup of water sitting on a scale. A way to solve the problem would be to first recognize that the water exerts a buoyant force upward on the finger, which students can recognize as being the reason why they feel lighter when they are in a swimming pool. By Newton's third law, the finger must hence exert a downward-pointing force on the water (labeled F[subscript B]). Since the water is not accelerating, the normal force from the beaker acting upward on the water (FN2) must increase to equal the sum of the weight of the water (F[subscript W]) and F[subscript B] (Newton's second law). By Newton's third law, the water must exert a force equal to F[subscript N2] down on the beaker. However, since the beaker is not accelerating, Newton's second law tells us that the normal force from the scale is equal to this increased F[subscript N2]. Via these chains of Newton's second and third laws, we can see that the reading on the scale will increase. (As Provided).
Anmerkungen	American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail: pubs@aapt.org; Web site: http://aapt.scitation.org/journal/pte
Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2024/1/01