The Missing 44 km/h
Sam's flight tracker showed his plane heading due north at 200 km/h through the air. A 50 km/h wind blew from the west, and the ground speed read 206 km/h.
Where did the missing 44 km/h go?
Page 1
Science · Honors Physics
Chapter 1: Kinematics with Calculus Readiness
Split a quantity into two that do not interfere.
Sam's flight tracker showed his plane heading due north at 200 km/h through the air. A 50 km/h wind blew from the west, and the ground speed read 206 km/h.
Where did the missing 44 km/h go?
Make your guess to turn the page.
Still to come: 10 pages · Lab · Words to Know · What We Learned · 4 questions · Explain It in Writing · Open Questions
The idea this lesson is working on — Students add the sizes of vectors as ordinary numbers, so 200 km/h and 50 km/h make 250 km/h whatever the angle. The book sets that against the plane, the law of cosines and the lab, where two components add to 6.83 m/s yet make a 5.00 m/s boat. Ask: are these two vectors along one line? The idea to reach is add by component, then recombine.
Split into two that do not interfere — Perpendicular components are independent, so a two-dimensional problem becomes two one-dimensional ones. That decomposition is the most useful single technique in mechanics, and it is the thread through this whole chapter.
About Stevin's wreath — Stevin published the clootcrans in 1586 and was proud enough of it to use it as his emblem. It is an argument from the impossibility of perpetual motion, not a measurement; the ball counts follow his figure as it is usually reproduced.